MDEV-7098 spider/bg.spider_fixes failed in buildbot with safe_mutex: Trying to unlock mutex conn->mta_conn_mutex that wasn't locked at storage/spider/spd_db_conn.cc, line 671

7 files changed, 1534 insertions, 539 deletions

diff --git a/storage/spider/ha_spider.cc b/storage/spider/ha_spider.cc
index fb453ddc637..5e7b5a1e8ce 100644
--- a/storage/spider/ha_spider.cc
+++ b/storage/spider/ha_spider.cc
@@ -2258,6 +2258,7 @@ int ha_spider::index_read_map_internal(
       }
 #endif
       spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
       {
         pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -2265,6 +2266,11 @@ int ha_spider::index_read_map_internal(
       }
       if ((error_num = dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
       {
+        if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+        {
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
+        }
         DBUG_RETURN(error_num);
       }
       if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -2286,11 +2292,15 @@ int ha_spider::index_read_map_internal(
       } else {
 #endif
         conn->need_mon = &need_mons[roop_count];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(this, conn,
           roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -2325,6 +2335,8 @@ int ha_spider::index_read_map_internal(
           result_list.quick_mode,
           &need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -2351,6 +2363,8 @@ int ha_spider::index_read_map_internal(
           DBUG_RETURN(check_error_mode_eof(error_num));
         }
         connection_ids[roop_count] = conn->connection_id;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         if (roop_count == link_ok)
@@ -2750,6 +2764,7 @@ int ha_spider::index_read_last_map_internal(
       }
 #endif
       spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
       {
         pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -2757,6 +2772,11 @@ int ha_spider::index_read_last_map_internal(
       }
       if ((error_num = dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
       {
+        if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+        {
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
+        }
         DBUG_RETURN(error_num);
       }
       if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -2775,11 +2795,15 @@ int ha_spider::index_read_last_map_internal(
       } else {
 #endif
         conn->need_mon = &need_mons[roop_count];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(this, conn,
           roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -2814,6 +2838,8 @@ int ha_spider::index_read_last_map_internal(
           result_list.quick_mode,
           &need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -2840,6 +2866,8 @@ int ha_spider::index_read_last_map_internal(
           DBUG_RETURN(check_error_mode_eof(error_num));
         }
         connection_ids[roop_count] = conn->connection_id;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         if (roop_count == link_ok)
@@ -3216,6 +3244,7 @@ int ha_spider::index_first_internal(
         }
 #endif
         spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
         {
           pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -3224,6 +3253,11 @@ int ha_spider::index_first_internal(
         if ((error_num =
           dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -3242,11 +3276,15 @@ int ha_spider::index_first_internal(
         } else {
 #endif
           conn->need_mon = &need_mons[roop_count];
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = TRUE;
           conn->mta_conn_mutex_unlock_later = TRUE;
           if ((error_num = spider_db_set_names(this, conn,
             roop_count)))
           {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -3281,6 +3319,8 @@ int ha_spider::index_first_internal(
             result_list.quick_mode,
             &need_mons[roop_count])
           ) {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             error_num = spider_db_errorno(conn);
@@ -3307,6 +3347,8 @@ int ha_spider::index_first_internal(
             DBUG_RETURN(check_error_mode_eof(error_num));
           }
           connection_ids[roop_count] = conn->connection_id;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           if (roop_count == link_ok)
@@ -3600,6 +3642,7 @@ int ha_spider::index_last_internal(
         }
 #endif
         spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
         {
           pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -3608,6 +3651,11 @@ int ha_spider::index_last_internal(
         if ((error_num =
           dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -3626,11 +3674,15 @@ int ha_spider::index_last_internal(
         } else {
 #endif
           conn->need_mon = &need_mons[roop_count];
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = TRUE;
           conn->mta_conn_mutex_unlock_later = TRUE;
           if ((error_num = spider_db_set_names(this, conn,
             roop_count)))
           {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -3665,6 +3717,8 @@ int ha_spider::index_last_internal(
             result_list.quick_mode,
             &need_mons[roop_count])
           ) {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             error_num = spider_db_errorno(conn);
@@ -3691,6 +3745,8 @@ int ha_spider::index_last_internal(
             DBUG_RETURN(check_error_mode_eof(error_num));
           }
           connection_ids[roop_count] = conn->connection_id;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           if (roop_count == link_ok)
@@ -4044,6 +4100,7 @@ int ha_spider::read_range_first_internal(
       }
 #endif
       spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
       {
         pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -4051,6 +4108,11 @@ int ha_spider::read_range_first_internal(
       }
       if ((error_num = dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
       {
+        if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+        {
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
+        }
         DBUG_RETURN(error_num);
       }
       if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -4069,11 +4131,15 @@ int ha_spider::read_range_first_internal(
       } else {
 #endif
         conn->need_mon = &need_mons[roop_count];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(this, conn,
           roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -4108,6 +4174,8 @@ int ha_spider::read_range_first_internal(
           result_list.quick_mode,
           &need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -4134,6 +4202,8 @@ int ha_spider::read_range_first_internal(
           DBUG_RETURN(check_error_mode_eof(error_num));
         }
         connection_ids[roop_count] = conn->connection_id;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         if (roop_count == link_ok)
@@ -4670,6 +4740,7 @@ int ha_spider::read_multi_range_first_internal(
           }
 #endif
           spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
           {
             pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -4678,6 +4749,11 @@ int ha_spider::read_multi_range_first_internal(
           if ((error_num =
             dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
           {
+            if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             DBUG_RETURN(error_num);
           }
           if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -4702,11 +4778,15 @@ int ha_spider::read_multi_range_first_internal(
           } else {
 #endif
             conn->need_mon = &need_mons[roop_count];
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = TRUE;
             conn->mta_conn_mutex_unlock_later = TRUE;
             if ((error_num = spider_db_set_names(this, conn,
               roop_count)))
             {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -4742,6 +4822,8 @@ int ha_spider::read_multi_range_first_internal(
                 result_list.quick_mode,
                 &need_mons[roop_count])
               ) {
+                DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+                DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
                 conn->mta_conn_mutex_lock_already = FALSE;
                 conn->mta_conn_mutex_unlock_later = FALSE;
                 error_num = spider_db_errorno(conn);
@@ -4770,6 +4852,8 @@ int ha_spider::read_multi_range_first_internal(
             if (!error_num)
             {
               connection_ids[roop_count] = conn->connection_id;
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               if (roop_count == link_ok)
@@ -5463,6 +5547,7 @@ int ha_spider::read_multi_range_first_internal(
           }
 #endif
           spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
           {
             pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -5471,6 +5556,11 @@ int ha_spider::read_multi_range_first_internal(
           if ((error_num =
             dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
           {
+            if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             DBUG_RETURN(error_num);
           }
           if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -5496,11 +5586,15 @@ int ha_spider::read_multi_range_first_internal(
           } else {
 #endif
             conn->need_mon = &need_mons[roop_count];
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = TRUE;
             conn->mta_conn_mutex_unlock_later = TRUE;
             if ((error_num = spider_db_set_names(this, conn,
               roop_count)))
             {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5542,6 +5636,8 @@ int ha_spider::read_multi_range_first_internal(
                 -1,
                 &need_mons[roop_count])
               ) {
+                DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+                DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
                 conn->mta_conn_mutex_lock_already = FALSE;
                 conn->mta_conn_mutex_unlock_later = FALSE;
                 error_num = spider_db_errorno(conn);
@@ -5577,6 +5673,8 @@ int ha_spider::read_multi_range_first_internal(
               result_list.quick_mode,
               &need_mons[roop_count])
             ) {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               error_num = spider_db_errorno(conn);
@@ -5603,6 +5701,8 @@ int ha_spider::read_multi_range_first_internal(
               break;
             }
             connection_ids[roop_count] = conn->connection_id;
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             if (roop_count == link_ok)
@@ -6110,6 +6210,7 @@ int ha_spider::read_multi_range_next(
           }
 #endif
           spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
           {
             pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -6118,6 +6219,11 @@ int ha_spider::read_multi_range_next(
           if ((error_num =
             dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
           {
+            if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             DBUG_RETURN(error_num);
           }
           if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -6142,11 +6248,15 @@ int ha_spider::read_multi_range_next(
           } else {
 #endif
             conn->need_mon = &need_mons[roop_count];
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = TRUE;
             conn->mta_conn_mutex_unlock_later = TRUE;
             if ((error_num = spider_db_set_names(this, conn,
               roop_count)))
             {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6182,6 +6292,8 @@ int ha_spider::read_multi_range_next(
                 result_list.quick_mode,
                 &need_mons[roop_count])
               ) {
+                DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+                DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
                 conn->mta_conn_mutex_lock_already = FALSE;
                 conn->mta_conn_mutex_unlock_later = FALSE;
                 error_num = spider_db_errorno(conn);
@@ -6210,6 +6322,8 @@ int ha_spider::read_multi_range_next(
             if (!error_num)
             {
               connection_ids[roop_count] = conn->connection_id;
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               if (roop_count == link_ok)
@@ -6907,6 +7021,7 @@ int ha_spider::read_multi_range_next(
           }
 #endif
           spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
           {
             pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -6915,6 +7030,11 @@ int ha_spider::read_multi_range_next(
           if ((error_num =
             dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
           {
+            if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             DBUG_RETURN(error_num);
           }
           if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -6940,11 +7060,15 @@ int ha_spider::read_multi_range_next(
           } else {
 #endif
             conn->need_mon = &need_mons[roop_count];
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = TRUE;
             conn->mta_conn_mutex_unlock_later = TRUE;
             if ((error_num = spider_db_set_names(this, conn,
               roop_count)))
             {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6986,6 +7110,8 @@ int ha_spider::read_multi_range_next(
                 -1,
                 &need_mons[roop_count])
               ) {
+                DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+                DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
                 conn->mta_conn_mutex_lock_already = FALSE;
                 conn->mta_conn_mutex_unlock_later = FALSE;
                 error_num = spider_db_errorno(conn);
@@ -7021,6 +7147,8 @@ int ha_spider::read_multi_range_next(
               result_list.quick_mode,
               &need_mons[roop_count])
             ) {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               error_num = spider_db_errorno(conn);
@@ -7047,6 +7175,8 @@ int ha_spider::read_multi_range_next(
               break;
             }
             connection_ids[roop_count] = conn->connection_id;
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             if (roop_count == link_ok)
@@ -7524,6 +7654,7 @@ int ha_spider::rnd_next_internal(
           sql_type = SPIDER_SQL_TYPE_HANDLER;
         }
         spider_db_handler *dbton_hdl = dbton_handler[conn->dbton_id];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
         {
           pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -7532,6 +7663,11 @@ int ha_spider::rnd_next_internal(
         if ((error_num =
           dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -7541,11 +7677,15 @@ int ha_spider::rnd_next_internal(
         }
         DBUG_PRINT("info",("spider sql_type=%lu", sql_type));
         conn->need_mon = &need_mons[roop_count];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(this, conn,
           roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -7580,6 +7720,8 @@ int ha_spider::rnd_next_internal(
           result_list.quick_mode,
           &need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -7606,6 +7748,8 @@ int ha_spider::rnd_next_internal(
           DBUG_RETURN(check_error_mode_eof(error_num));
         }
         connection_ids[roop_count] = conn->connection_id;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         if (roop_count == link_ok)
@@ -8116,6 +8260,7 @@ int ha_spider::ft_read_internal(
         uint dbton_id = share->use_sql_dbton_ids[roop_count];
         spider_db_handler *dbton_hdl = dbton_handler[dbton_id];
         SPIDER_CONN *conn = conns[roop_count];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(
           SPIDER_SQL_TYPE_SELECT_SQL))
         {
@@ -8125,6 +8270,12 @@ int ha_spider::ft_read_internal(
         if ((error_num = dbton_hdl->set_sql_for_exec(
           SPIDER_SQL_TYPE_SELECT_SQL, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(
+            SPIDER_SQL_TYPE_SELECT_SQL))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -8134,10 +8285,14 @@ int ha_spider::ft_read_internal(
           SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
         }
         conn->need_mon = &need_mons[roop_count];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(this, conn, roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -8171,6 +8326,8 @@ int ha_spider::ft_read_internal(
           result_list.quick_mode,
           &need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -8197,6 +8354,8 @@ int ha_spider::ft_read_internal(
           DBUG_RETURN(check_error_mode_eof(error_num));
         }
         connection_ids[roop_count] = conn->connection_id;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         if (roop_count == link_ok)
@@ -10455,9 +10614,12 @@ void ha_spider::bulk_req_exec()
     if (conn->bulk_access_requests)
     {
       spider_bg_conn_wait(conn);
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       pthread_mutex_lock(&conn->mta_conn_mutex);
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
       conn->need_mon = &need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       /* currently only used for HS */
@@ -10475,6 +10637,8 @@ void ha_spider::bulk_req_exec()
       conn->bulk_access_sended += conn->bulk_access_requests;
 */
       conn->bulk_access_requests = 0;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -12217,6 +12381,7 @@ int ha_spider::drop_tmp_tables()
         uint dbton_id = share->use_sql_dbton_ids[roop_count];
         spider_db_handler *dbton_hdl = dbton_handler[dbton_id];
         SPIDER_CONN *conn = conns[roop_count];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(
           SPIDER_SQL_TYPE_TMP_SQL))
         {
@@ -12226,6 +12391,12 @@ int ha_spider::drop_tmp_tables()
         if ((error_num = dbton_hdl->set_sql_for_exec(
           SPIDER_SQL_TYPE_TMP_SQL, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(
+            SPIDER_SQL_TYPE_TMP_SQL))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -12235,10 +12406,14 @@ int ha_spider::drop_tmp_tables()
           SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
         }
         conn->need_mon = &need_mon;
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((tmp_error_num = spider_db_set_names(this, conn, roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -12275,6 +12450,8 @@ int ha_spider::drop_tmp_tables()
             -1,
             &need_mons[roop_count])
           ) {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             tmp_error_num = spider_db_errorno(conn);
@@ -12300,6 +12477,8 @@ int ha_spider::drop_tmp_tables()
             }
             error_num = tmp_error_num;
           } else {
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
diff --git a/storage/spider/spd_conn.cc b/storage/spider/spd_conn.cc
index c1c2ce07476..30296215952 100644
--- a/storage/spider/spd_conn.cc
+++ b/storage/spider/spd_conn.cc
@@ -2385,6 +2385,7 @@ void *spider_bg_conn_action(
           sql_type = SPIDER_SQL_TYPE_SELECT_HS;
         }
 #endif
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
         {
           pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -2414,6 +2415,8 @@ void *spider_bg_conn_action(
         if (!result_list->bgs_error)
         {
           conn->need_mon = &spider->need_mons[conn->link_idx];
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = TRUE;
           conn->mta_conn_mutex_unlock_later = TRUE;
 #ifdef HA_CAN_BULK_ACCESS
@@ -2491,6 +2494,8 @@ void *spider_bg_conn_action(
 #ifdef HA_CAN_BULK_ACCESS
           }
 #endif
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -2501,11 +2506,14 @@ void *spider_bg_conn_action(
         }
       } else {
         spider->connection_ids[conn->link_idx] = conn->connection_id;
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_unlock_later = TRUE;
         result_list->bgs_error =
           spider_db_store_result(spider, conn->link_idx, result_list->table);
         if ((result_list->bgs_error_with_message = thd->is_error()))
           strmov(result_list->bgs_error_msg, spider_stmt_da_message(thd));
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_unlock_later = FALSE;
       }
       conn->bg_search = FALSE;
@@ -2569,12 +2577,26 @@ void *spider_bg_conn_action(
     {
       DBUG_PRINT("info",("spider bg exec sql start"));
       spider = (ha_spider*) conn->bg_target;
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = &spider->need_mons[conn->link_idx];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       *conn->bg_error_num = spider_db_query_with_set_names(
         conn->bg_sql_type,
         spider,
         conn,
         conn->link_idx
       );
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       conn->bg_exec_sql = FALSE;
       continue;
     }
diff --git a/storage/spider/spd_db_conn.cc b/storage/spider/spd_db_conn.cc
index 13ff6c568de..f77603d0d3a 100644
--- a/storage/spider/spd_db_conn.cc
+++ b/storage/spider/spd_db_conn.cc
@@ -208,23 +208,14 @@ int spider_db_ping(
     DBUG_PRINT("info", ("spider thd->query_id is %lld",
       spider->trx->thd->query_id));
 #endif
-  if (!conn->mta_conn_mutex_lock_already)
-  {
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = &spider->need_mons[link_idx];
-  }
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
   DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
   if (conn->server_lost || conn->queued_connect)
   {
     if ((error_num = spider_db_connect(spider->share, conn,
       spider->conn_link_idx[link_idx])))
     {
-      if (!conn->mta_conn_mutex_unlock_later)
-      {
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-      }
+      pthread_mutex_assert_owner(&conn->mta_conn_mutex);
       DBUG_RETURN(error_num);
     }
     conn->server_lost = FALSE;
@@ -238,11 +229,7 @@ int spider_db_ping(
     {
       DBUG_PRINT("info", ("spider conn=%p SERVER_LOST", conn));
       conn->server_lost = TRUE;
-      if (!conn->mta_conn_mutex_unlock_later)
-      {
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-      }
+      pthread_mutex_assert_owner(&conn->mta_conn_mutex);
       DBUG_RETURN(error_num);
     }
     if((error_num = conn->db_conn->ping()))
@@ -250,20 +237,12 @@ int spider_db_ping(
       spider_db_disconnect(conn);
       DBUG_PRINT("info", ("spider conn=%p SERVER_LOST", conn));
       conn->server_lost = TRUE;
-      if (!conn->mta_conn_mutex_unlock_later)
-      {
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-      }
+      pthread_mutex_assert_owner(&conn->mta_conn_mutex);
       DBUG_RETURN(error_num);
     }
   }
   conn->ping_time = (time_t) time((time_t*) 0);
-  if (!conn->mta_conn_mutex_unlock_later)
-  {
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-  }
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
 }
 
@@ -303,6 +282,7 @@ int spider_db_conn_queue_action(
     conn->queued_connect = FALSE;
   }
 
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (conn->conn_kind == SPIDER_CONN_KIND_MYSQL)
   {
@@ -551,7 +531,6 @@ int spider_db_before_query(
   int *need_mon
 ) {
   int error_num;
-  bool tmp_mta_conn_mutex_lock_already;
   DBUG_ENTER("spider_db_before_query");
   DBUG_ASSERT(need_mon);
 #ifndef WITHOUT_SPIDER_BG_SEARCH
@@ -559,25 +538,18 @@ int spider_db_before_query(
     spider_bg_conn_break(conn, NULL);
 #endif
   conn->in_before_query = TRUE;
-  if (!conn->mta_conn_mutex_lock_already)
-  {
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = need_mon;
-  }
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
   DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
-  tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-  conn->mta_conn_mutex_lock_already = TRUE;
   if ((error_num = spider_db_conn_queue_action(conn)))
   {
     conn->in_before_query = FALSE;
-    conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
+    pthread_mutex_assert_owner(&conn->mta_conn_mutex);
     DBUG_RETURN(error_num);
   }
-  conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
   if (conn->server_lost)
   {
     conn->in_before_query = FALSE;
+    pthread_mutex_assert_owner(&conn->mta_conn_mutex);
     DBUG_RETURN(CR_SERVER_GONE_ERROR);
   }
   DBUG_PRINT("info", ("spider conn[%p]->quick_target=%p",
@@ -604,6 +576,7 @@ int spider_db_before_query(
         ) {
           conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
           conn->in_before_query = FALSE;
+          pthread_mutex_assert_owner(&conn->mta_conn_mutex);
           DBUG_RETURN(error_num);
         }
       }
@@ -619,6 +592,7 @@ int spider_db_before_query(
     }
   }
   conn->in_before_query = FALSE;
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
 }
 
@@ -631,6 +605,7 @@ int spider_db_query(
 ) {
   int error_num;
   DBUG_ENTER("spider_db_query");
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (conn->conn_kind == SPIDER_CONN_KIND_MYSQL)
   {
@@ -673,6 +648,7 @@ int spider_db_errorno(
   int error_num;
   DBUG_ENTER("spider_db_errorno");
   DBUG_ASSERT(conn->need_mon);
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (conn->conn_kind == SPIDER_CONN_KIND_MYSQL)
   {
@@ -687,6 +663,7 @@ int spider_db_errorno(
       }
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -708,6 +685,7 @@ int spider_db_errorno(
         }
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -720,6 +698,7 @@ int spider_db_errorno(
         conn->error_length = strlen(conn->error_str);
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -745,6 +724,7 @@ int spider_db_errorno(
         }
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -766,6 +746,7 @@ int spider_db_errorno(
       }
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -782,6 +763,7 @@ int spider_db_errorno(
       conn->server_lost = TRUE;
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -791,6 +773,7 @@ int spider_db_errorno(
       *conn->need_mon = 0;
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -813,6 +796,7 @@ int spider_db_errorno(
     *conn->need_mon = ER_SPIDER_HS_NUM;
     if (!conn->mta_conn_mutex_unlock_later)
     {
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
@@ -821,6 +805,7 @@ int spider_db_errorno(
 #endif
   if (!conn->mta_conn_mutex_unlock_later)
   {
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   }
@@ -843,33 +828,25 @@ int spider_db_set_names_internal(
   int all_link_idx,
   int *need_mon
 ) {
-  bool tmp_mta_conn_mutex_lock_already;
   DBUG_ENTER("spider_db_set_names_internal");
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (conn->conn_kind == SPIDER_CONN_KIND_MYSQL)
   {
 #endif
-    if (!conn->mta_conn_mutex_lock_already)
-    {
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      conn->need_mon = need_mon;
-    }
+    pthread_mutex_assert_owner(&conn->mta_conn_mutex);
     DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     if (
       !conn->access_charset ||
       share->access_charset->cset != conn->access_charset->cset
     ) {
-      tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-      conn->mta_conn_mutex_lock_already = TRUE;
       if (
         spider_db_before_query(conn, need_mon) ||
         conn->db_conn->set_character_set(share->access_charset->csname)
       ) {
-        conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
         DBUG_RETURN(spider_db_errorno(conn));
       }
-      conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
       conn->access_charset = share->access_charset;
     }
     if (
@@ -884,13 +861,10 @@ int spider_db_set_names_internal(
     ) {
       DBUG_PRINT("info",("spider all_link_idx=%d db=%s", all_link_idx,
         share->tgt_dbs[all_link_idx]));
-      tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-      conn->mta_conn_mutex_lock_already = TRUE;
       if (
         spider_db_before_query(conn, need_mon) ||
         conn->db_conn->select_db(share->tgt_dbs[all_link_idx])
       ) {
-        conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
         DBUG_RETURN(spider_db_errorno(conn));
       }
       conn->default_database.length(0);
@@ -900,12 +874,6 @@ int spider_db_set_names_internal(
       conn->default_database.q_append(share->tgt_dbs[all_link_idx],
         share->tgt_dbs_lengths[all_link_idx] + 1);
       conn->default_database.length(share->tgt_dbs_lengths[all_link_idx]);
-      conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-    }
-    if (!conn->mta_conn_mutex_unlock_later)
-    {
-      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   }
@@ -934,19 +902,11 @@ int spider_db_query_with_set_names(
   spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
   DBUG_ENTER("spider_db_query_with_set_names");
 
-/*
-  pthread_mutex_lock(&conn->mta_conn_mutex);
-  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-*/
-  conn->need_mon = &spider->need_mons[link_idx];
-  conn->mta_conn_mutex_lock_already = TRUE;
-  conn->mta_conn_mutex_unlock_later = TRUE;
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
-    conn->mta_conn_mutex_lock_already = FALSE;
-    conn->mta_conn_mutex_unlock_later = FALSE;
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
     if (
       share->monitoring_kind[link_idx] &&
       spider->need_mons[link_idx]
@@ -977,8 +937,6 @@ int spider_db_query_with_set_names(
     -1,
     &spider->need_mons[link_idx])
   ) {
-    conn->mta_conn_mutex_lock_already = FALSE;
-    conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     if (
       share->monitoring_kind[link_idx] &&
@@ -1002,10 +960,6 @@ int spider_db_query_with_set_names(
     }
     DBUG_RETURN(error_num);
   }
-  conn->mta_conn_mutex_lock_already = FALSE;
-  conn->mta_conn_mutex_unlock_later = FALSE;
-  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-  pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
 }
 
@@ -1019,15 +973,16 @@ int spider_db_query_for_bulk_update(
   SPIDER_SHARE *share = spider->share;
   DBUG_ENTER("spider_db_query_for_bulk_update");
 
-/*
-  pthread_mutex_lock(&conn->mta_conn_mutex);
-  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-*/
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -1063,6 +1018,8 @@ int spider_db_query_for_bulk_update(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
@@ -1109,6 +1066,8 @@ int spider_db_query_for_bulk_update(
   }
   if (error_num > 0 && !conn->db_conn->is_dup_entry_error(error_num))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -1135,6 +1094,8 @@ int spider_db_query_for_bulk_update(
     }
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -3644,6 +3605,7 @@ int spider_db_store_result(
         ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -3660,6 +3622,7 @@ int spider_db_store_result(
         ) {
           if (!conn->mta_conn_mutex_unlock_later)
           {
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
             pthread_mutex_unlock(&conn->mta_conn_mutex);
           }
@@ -3691,6 +3654,7 @@ int spider_db_store_result(
           ) {
             if (!conn->mta_conn_mutex_unlock_later)
             {
+              DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&conn->mta_conn_mutex);
             }
@@ -3734,6 +3698,7 @@ int spider_db_store_result(
           ) {
             if (!conn->mta_conn_mutex_unlock_later)
             {
+              DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&conn->mta_conn_mutex);
             }
@@ -3773,6 +3738,7 @@ int spider_db_store_result(
         {
           if (!conn->mta_conn_mutex_unlock_later)
           {
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
             pthread_mutex_unlock(&conn->mta_conn_mutex);
           }
@@ -3801,6 +3767,7 @@ int spider_db_store_result(
 #endif
         if (!conn->mta_conn_mutex_unlock_later && !call_db_errorno)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -3808,6 +3775,7 @@ int spider_db_store_result(
       } else {
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -3851,6 +3819,7 @@ int spider_db_store_result(
         result_list->limit_num -= current->prev->record_num;
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -3874,6 +3843,7 @@ int spider_db_store_result(
           } else {
             if (!conn->mta_conn_mutex_unlock_later)
             {
+              DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&conn->mta_conn_mutex);
             }
@@ -3885,6 +3855,7 @@ int spider_db_store_result(
         spider->quick_targets[link_idx] = spider;
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -4043,6 +4014,7 @@ int spider_db_store_result(
         ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
       if (!conn->mta_conn_mutex_unlock_later)
       {
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&conn->mta_conn_mutex);
       }
@@ -4068,6 +4040,7 @@ int spider_db_store_result(
       } else {
         if (!conn->mta_conn_mutex_unlock_later)
         {
+          DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&conn->mta_conn_mutex);
         }
@@ -4078,6 +4051,7 @@ int spider_db_store_result(
     result_list->hs_has_result = TRUE;
     if (!conn->mta_conn_mutex_unlock_later)
     {
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
@@ -4163,15 +4137,15 @@ int spider_db_bulk_store_result(
   error_num = spider_db_bulk_open_handler(spider, conn, link_idx);
   if (!discard_result)
   {
-    bool tmp_mta_conn_mutex_unlock_later;
-    tmp_mta_conn_mutex_unlock_later = conn->mta_conn_mutex_unlock_later;
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((tmp_error_num = spider_db_store_result(spider, link_idx,
       spider->get_table())))
     {
       error_num = tmp_error_num;
     }
-    conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
+    conn->mta_conn_mutex_unlock_later = FALSE;
   } else {
     if (spider->connection_ids[link_idx] == conn->connection_id)
       spider_db_discard_result(spider, link_idx, conn);
@@ -4381,10 +4355,14 @@ int spider_db_seek_next(
               SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
             }
             conn->need_mon = &spider->need_mons[roop_count];
+            DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = TRUE;
             conn->mta_conn_mutex_unlock_later = TRUE;
             if ((error_num = spider_db_set_names(spider, conn, roop_count)))
             {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -4420,6 +4398,8 @@ int spider_db_seek_next(
               result_list->quick_mode,
               &spider->need_mons[roop_count])
             ) {
+              DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
               conn->mta_conn_mutex_lock_already = FALSE;
               conn->mta_conn_mutex_unlock_later = FALSE;
               error_num = spider_db_errorno(conn);
@@ -4447,6 +4427,8 @@ int spider_db_seek_next(
               DBUG_RETURN(error_num);
             }
             spider->connection_ids[roop_count] = conn->connection_id;
+            DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
             conn->mta_conn_mutex_lock_already = FALSE;
             conn->mta_conn_mutex_unlock_later = FALSE;
             if (roop_count == link_ok)
@@ -4487,6 +4469,8 @@ int spider_db_seek_next(
           }
         } else {
           spider->connection_ids[link_idx] = conn->connection_id;
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+          DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_unlock_later = TRUE;
           if ((error_num = spider_db_store_result(spider, link_idx, table)))
           {
@@ -4613,6 +4597,7 @@ int spider_db_seek_last(
       }
       conn = spider->conns[roop_count];
       spider_db_handler *dbton_handler = spider->dbton_handler[conn->dbton_id];
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
       {
         pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -4620,6 +4605,11 @@ int spider_db_seek_last(
       }
       if ((error_num = dbton_handler->set_sql_for_exec(sql_type, roop_count)))
       {
+        if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
+        {
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
+        }
         DBUG_RETURN(error_num);
       }
       if (!dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
@@ -4629,10 +4619,14 @@ int spider_db_seek_last(
       }
       DBUG_PRINT("info",("spider sql_type=%lu", sql_type));
       conn->need_mon = &spider->need_mons[roop_count];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if ((error_num = spider_db_set_names(spider, conn, roop_count)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -4667,6 +4661,8 @@ int spider_db_seek_last(
         result_list->quick_mode,
         &spider->need_mons[roop_count])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         error_num = spider_db_errorno(conn);
@@ -4693,6 +4689,8 @@ int spider_db_seek_last(
         DBUG_RETURN(error_num);
       }
       spider->connection_ids[roop_count] = conn->connection_id;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       if (roop_count == link_ok)
@@ -4813,6 +4811,7 @@ int spider_db_seek_last(
     }
     conn = spider->conns[roop_count];
     spider_db_handler *dbton_handler = spider->dbton_handler[conn->dbton_id];
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
     {
       pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -4820,6 +4819,11 @@ int spider_db_seek_last(
     }
     if ((error_num = dbton_handler->set_sql_for_exec(sql_type, roop_count)))
     {
+      if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
@@ -4829,10 +4833,14 @@ int spider_db_seek_last(
     }
     DBUG_PRINT("info",("spider sql_type=%lu", sql_type));
     conn->need_mon = &spider->need_mons[roop_count];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_set_names(spider, conn, roop_count)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -4867,6 +4875,8 @@ int spider_db_seek_last(
       result_list->quick_mode,
       &spider->need_mons[roop_count])
     ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       error_num = spider_db_errorno(conn);
@@ -4893,6 +4903,8 @@ int spider_db_seek_last(
       DBUG_RETURN(error_num);
     }
     spider->connection_ids[roop_count] = conn->connection_id;
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     if (roop_count == link_ok)
@@ -5561,8 +5573,6 @@ int spider_db_bulk_insert(
 #endif
   SPIDER_SHARE *share = spider->share;
   THD *thd = spider->trx->thd;
-  bool mta_conn_mutex_lock_already_backup;
-  bool mta_conn_mutex_unlock_later_backup;
   DBUG_ENTER("spider_db_bulk_insert");
 
   if (!bulk_end)
@@ -5617,61 +5627,50 @@ int spider_db_bulk_insert(
           sql_type = SPIDER_SQL_TYPE_INSERT_SQL;
           conn = spider->conns[roop_count2];
           dbton_handler = spider->dbton_handler[conn->dbton_id];
-          mta_conn_mutex_lock_already_backup =
-            conn->mta_conn_mutex_lock_already;
-          mta_conn_mutex_unlock_later_backup =
-            conn->mta_conn_mutex_unlock_later;
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
           {
-            if (!mta_conn_mutex_lock_already_backup)
-            {
-              pthread_mutex_lock(&conn->mta_conn_mutex);
-              SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            }
+            pthread_mutex_lock(&conn->mta_conn_mutex);
+            SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
           }
           if ((error_num = dbton_handler->set_sql_for_exec(sql_type,
             roop_count2)))
           {
+            if (dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             DBUG_RETURN(error_num);
           }
           if (!dbton_handler->need_lock_before_set_sql_for_exec(sql_type))
           {
-            if (!mta_conn_mutex_lock_already_backup)
-            {
-              pthread_mutex_lock(&conn->mta_conn_mutex);
-              SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            }
+            pthread_mutex_lock(&conn->mta_conn_mutex);
+            SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
           }
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
         } else {
           sql_type = SPIDER_SQL_TYPE_INSERT_HS;
           conn = spider->hs_w_conns[roop_count2];
           dbton_handler = spider->dbton_handler[conn->dbton_id];
-          mta_conn_mutex_lock_already_backup =
-            conn->mta_conn_mutex_lock_already;
-          mta_conn_mutex_unlock_later_backup =
-            conn->mta_conn_mutex_unlock_later;
-          if (!mta_conn_mutex_lock_already_backup)
-          {
-            pthread_mutex_lock(&conn->mta_conn_mutex);
-            SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          }
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+          pthread_mutex_lock(&conn->mta_conn_mutex);
+          SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
         }
 #endif
         conn->need_mon = &spider->need_mons[roop_count2];
+        DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = TRUE;
         conn->mta_conn_mutex_unlock_later = TRUE;
         if ((error_num = spider_db_set_names(spider, conn, roop_count2)))
         {
-          conn->mta_conn_mutex_lock_already =
-            mta_conn_mutex_lock_already_backup;
-          conn->mta_conn_mutex_unlock_later =
-            mta_conn_mutex_unlock_later_backup;
-          if (!mta_conn_mutex_unlock_later_backup)
-          {
-            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            pthread_mutex_unlock(&conn->mta_conn_mutex);
-          }
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+          conn->mta_conn_mutex_lock_already = FALSE;
+          conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
           if (
             share->monitoring_kind[roop_count2] &&
             spider->need_mons[roop_count2]
@@ -5709,15 +5708,12 @@ int spider_db_bulk_insert(
           {
             conn->db_conn->set_dup_key_idx(spider, roop_count2);
           }
-          conn->mta_conn_mutex_lock_already =
-            mta_conn_mutex_lock_already_backup;
-          conn->mta_conn_mutex_unlock_later =
-            mta_conn_mutex_unlock_later_backup;
-          if (!mta_conn_mutex_unlock_later_backup)
-          {
-            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            pthread_mutex_unlock(&conn->mta_conn_mutex);
-          }
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+          conn->mta_conn_mutex_lock_already = FALSE;
+          conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
           if (
             error_num != ER_DUP_ENTRY &&
             error_num != ER_DUP_KEY &&
@@ -5743,8 +5739,10 @@ int spider_db_bulk_insert(
           }
           DBUG_RETURN(error_num);
         }
-        conn->mta_conn_mutex_lock_already = mta_conn_mutex_lock_already_backup;
-        conn->mta_conn_mutex_unlock_later = mta_conn_mutex_unlock_later_backup;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
         if (conn->conn_kind != SPIDER_CONN_KIND_MYSQL)
         {
@@ -5780,11 +5778,8 @@ int spider_db_bulk_insert(
           }
         }
 #endif
-        if (!mta_conn_mutex_unlock_later_backup)
-        {
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-        }
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
         if (first_insert_link_idx == -1)
         {
           first_insert_link_idx = roop_count2;
@@ -5793,14 +5788,12 @@ int spider_db_bulk_insert(
       }
 
       conn = first_insert_conn;
-      mta_conn_mutex_lock_already_backup = conn->mta_conn_mutex_lock_already;
-      mta_conn_mutex_unlock_later_backup = conn->mta_conn_mutex_unlock_later;
-      if (!mta_conn_mutex_lock_already_backup)
-      {
-        pthread_mutex_lock(&conn->mta_conn_mutex);
-        SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      }
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
       conn->need_mon = &spider->need_mons[first_insert_link_idx];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider->sql_kinds & SPIDER_SQL_KIND_SQL)
@@ -5822,15 +5815,12 @@ int spider_db_bulk_insert(
         else if ((error_num = dbton_handler->
           show_last_insert_id(first_insert_link_idx, last_insert_id)))
         {
-          conn->mta_conn_mutex_lock_already =
-            mta_conn_mutex_lock_already_backup;
-          conn->mta_conn_mutex_unlock_later =
-            mta_conn_mutex_unlock_later_backup;
-          if (!mta_conn_mutex_unlock_later_backup)
-          {
-            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            pthread_mutex_unlock(&conn->mta_conn_mutex);
-          }
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+          conn->mta_conn_mutex_lock_already = FALSE;
+          conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
           DBUG_RETURN(error_num);
         }
         table->next_number_field->set_notnull();
@@ -5840,25 +5830,21 @@ int spider_db_bulk_insert(
           (error_num = table->next_number_field->store(
             last_insert_id, TRUE))
         ) {
-          conn->mta_conn_mutex_lock_already =
-            mta_conn_mutex_lock_already_backup;
-          conn->mta_conn_mutex_unlock_later =
-            mta_conn_mutex_unlock_later_backup;
-          if (!mta_conn_mutex_unlock_later_backup)
-          {
-            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            pthread_mutex_unlock(&conn->mta_conn_mutex);
-          }
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+          conn->mta_conn_mutex_lock_already = FALSE;
+          conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
           DBUG_RETURN(error_num);
         }
       }
-      conn->mta_conn_mutex_lock_already = mta_conn_mutex_lock_already_backup;
-      conn->mta_conn_mutex_unlock_later = mta_conn_mutex_unlock_later_backup;
-      if (!mta_conn_mutex_unlock_later_backup)
-      {
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       spider->store_last_insert_id = 0;
 #ifdef HA_CAN_BULK_ACCESS
     }
@@ -5902,8 +5888,11 @@ int spider_db_bulk_bulk_insert(
       conn = spider->hs_w_conns[roop_count2];
     }
 #endif
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((tmp_error_num = spider_db_bulk_open_handler(spider, conn,
@@ -5911,6 +5900,8 @@ int spider_db_bulk_bulk_insert(
     {
       error_num = tmp_error_num;
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
@@ -5959,9 +5950,12 @@ int spider_db_bulk_bulk_insert(
   }
 
   conn = first_insert_conn;
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[first_insert_link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if (table->next_number_field &&
@@ -5988,6 +5982,8 @@ int spider_db_bulk_bulk_insert(
       error_num = tmp_error_num;
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6115,6 +6111,7 @@ int spider_db_bulk_update_size_limit(
     ) {
       conn = spider->conns[roop_count];
       spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       if (dbton_hdl->need_lock_before_set_sql_for_exec(
         SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
       {
@@ -6124,6 +6121,12 @@ int spider_db_bulk_update_size_limit(
       if ((error_num = dbton_hdl->set_sql_for_exec(
         SPIDER_SQL_TYPE_BULK_UPDATE_SQL, roop_count)))
       {
+        if (dbton_hdl->need_lock_before_set_sql_for_exec(
+          SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
+        {
+          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&conn->mta_conn_mutex);
+        }
         DBUG_RETURN(error_num);
       }
       if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -6134,7 +6137,11 @@ int spider_db_bulk_update_size_limit(
       }
       if ((error_num = spider_db_query_for_bulk_update(
         spider, conn, roop_count, &dup_key_found)))
+      {
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         DBUG_RETURN(error_num);
+      }
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     }
     spider->reset_sql_sql(SPIDER_SQL_TYPE_BULK_UPDATE_SQL);
   } else {
@@ -6200,6 +6207,7 @@ int spider_db_bulk_update_end(
         ) {
           conn = spider->conns[roop_count];
           spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           if (dbton_hdl->need_lock_before_set_sql_for_exec(
             SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
           {
@@ -6209,14 +6217,14 @@ int spider_db_bulk_update_end(
           if ((error_num = dbton_hdl->set_sql_for_exec(
             SPIDER_SQL_TYPE_BULK_UPDATE_SQL, roop_count)))
           {
+            if (dbton_hdl->need_lock_before_set_sql_for_exec(
+              SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
+            {
+              SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+              pthread_mutex_unlock(&conn->mta_conn_mutex);
+            }
             if (error_num == ER_SPIDER_COND_SKIP_NUM)
             {
-              if (dbton_hdl->need_lock_before_set_sql_for_exec(
-                SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
-              {
-                SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-                pthread_mutex_unlock(&conn->mta_conn_mutex);
-              }
               continue;
             }
             DBUG_RETURN(error_num);
@@ -6229,7 +6237,11 @@ int spider_db_bulk_update_end(
           }
           if ((error_num = spider_db_query_for_bulk_update(
             spider, conn, roop_count, dup_key_found)))
+          {
+            pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
             goto error_query;
+          }
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         }
       }
       if (error_num != HA_ERR_END_OF_FILE)
@@ -6254,6 +6266,7 @@ int spider_db_bulk_update_end(
       ) {
         conn = spider->conns[roop_count];
         spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
         if (dbton_hdl->need_lock_before_set_sql_for_exec(
           SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
         {
@@ -6263,6 +6276,12 @@ int spider_db_bulk_update_end(
         if ((error_num = dbton_hdl->set_sql_for_exec(
           SPIDER_SQL_TYPE_BULK_UPDATE_SQL, roop_count)))
         {
+          if (dbton_hdl->need_lock_before_set_sql_for_exec(
+            SPIDER_SQL_TYPE_BULK_UPDATE_SQL))
+          {
+            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&conn->mta_conn_mutex);
+          }
           DBUG_RETURN(error_num);
         }
         if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -6273,7 +6292,11 @@ int spider_db_bulk_update_end(
         }
         if ((error_num = spider_db_query_for_bulk_update(
           spider, conn, roop_count, dup_key_found)))
+        {
+          pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
           goto error_last_query;
+        }
+        pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       }
     }
   }
@@ -6341,6 +6364,7 @@ int spider_db_update(
 #if defined(MARIADB_BASE_VERSION) && MYSQL_VERSION_ID >= 100000
     conn->ignore_dup_key = spider->ignore_dup_key;
 #endif
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_hdl->need_lock_before_set_sql_for_exec(
       SPIDER_SQL_TYPE_UPDATE_SQL))
     {
@@ -6350,6 +6374,12 @@ int spider_db_update(
     if ((error_num = dbton_hdl->set_sql_for_exec(
       SPIDER_SQL_TYPE_UPDATE_SQL, roop_count)))
     {
+      if (dbton_hdl->need_lock_before_set_sql_for_exec(
+        SPIDER_SQL_TYPE_UPDATE_SQL))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -6359,10 +6389,14 @@ int spider_db_update(
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     }
     conn->need_mon = &spider->need_mons[roop_count];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_set_names(spider, conn, roop_count)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6397,6 +6431,8 @@ int spider_db_update(
       -1,
       &spider->need_mons[roop_count])
     ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       error_num = spider_db_errorno(conn);
@@ -6435,6 +6471,8 @@ int spider_db_update(
       if ((error_num = dbton_hdl->append_insert_for_recovery(
         SPIDER_SQL_TYPE_INSERT_SQL, roop_count)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6449,6 +6487,8 @@ int spider_db_update(
         -1,
         &spider->need_mons[roop_count])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         error_num = spider_db_errorno(conn);
@@ -6478,6 +6518,8 @@ int spider_db_update(
         DBUG_RETURN(error_num);
       }
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6666,6 +6708,7 @@ int spider_db_direct_update(
     }
 #endif
     spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
     {
       pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -6673,6 +6716,11 @@ int spider_db_direct_update(
     }
     if ((error_num = dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
     {
+      if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -6688,10 +6736,14 @@ int spider_db_direct_update(
     } else {
 #endif
       conn->need_mon = &spider->need_mons[roop_count];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if ((error_num = spider_db_set_names(spider, conn, roop_count)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6729,6 +6781,8 @@ int spider_db_direct_update(
         ) &&
         (error_num != HA_ERR_FOUND_DUPP_KEY || !spider->ignore_dup_key)
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         error_num = spider_db_errorno(conn);
@@ -6795,6 +6849,8 @@ int spider_db_direct_update(
           {
             error_num = spider_db_errorno(conn);
           }
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6803,11 +6859,13 @@ int spider_db_direct_update(
         }
       }
 #endif
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
 #ifdef HA_CAN_BULK_ACCESS
     }
 #endif
-    conn->mta_conn_mutex_lock_already = FALSE;
-    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   }
@@ -6852,8 +6910,11 @@ int spider_db_bulk_direct_update(
       conn = spider->hs_w_conns[roop_count];
     }
 #endif
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((tmp_error_num = spider_db_bulk_open_handler(spider, conn,
@@ -6899,6 +6960,8 @@ int spider_db_bulk_direct_update(
         {
           error_num = spider_db_errorno(conn);
         }
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6907,6 +6970,8 @@ int spider_db_bulk_direct_update(
       }
     }
 #endif
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -6963,6 +7028,7 @@ int spider_db_delete(
   ) {
     conn = spider->conns[roop_count];
     spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_hdl->need_lock_before_set_sql_for_exec(
       SPIDER_SQL_TYPE_DELETE_SQL))
     {
@@ -6972,6 +7038,12 @@ int spider_db_delete(
     if ((error_num = dbton_hdl->set_sql_for_exec(
       SPIDER_SQL_TYPE_DELETE_SQL, roop_count)))
     {
+      if (dbton_hdl->need_lock_before_set_sql_for_exec(
+        SPIDER_SQL_TYPE_DELETE_SQL))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -6980,9 +7052,27 @@ int spider_db_delete(
       pthread_mutex_lock(&conn->mta_conn_mutex);
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     }
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_query_with_set_names(
       SPIDER_SQL_TYPE_DELETE_SQL, spider, conn, roop_count)))
+    {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       DBUG_RETURN(error_num);
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
+    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    pthread_mutex_unlock(&conn->mta_conn_mutex);
     result_list->update_sqls[roop_count].length(0);
   }
   if ((error_num = spider->reset_sql_sql(SPIDER_SQL_TYPE_DELETE_SQL)))
@@ -7094,6 +7184,7 @@ int spider_db_direct_delete(
     }
 #endif
     spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
     {
       pthread_mutex_lock(&conn->mta_conn_mutex);
@@ -7101,6 +7192,11 @@ int spider_db_direct_delete(
     }
     if ((error_num = dbton_hdl->set_sql_for_exec(sql_type, roop_count)))
     {
+      if (dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_hdl->need_lock_before_set_sql_for_exec(sql_type))
@@ -7116,10 +7212,14 @@ int spider_db_direct_delete(
     } else {
 #endif
       conn->need_mon = &spider->need_mons[roop_count];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if ((error_num = spider_db_set_names(spider, conn, roop_count)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -7154,6 +7254,8 @@ int spider_db_direct_delete(
         -1,
         &spider->need_mons[roop_count])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         error_num = spider_db_errorno(conn);
@@ -7179,6 +7281,8 @@ int spider_db_direct_delete(
         }
         DBUG_RETURN(error_num);
       }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
@@ -7271,6 +7375,7 @@ int spider_db_delete_all_rows(
     uint dbton_id = share->use_sql_dbton_ids[roop_count];
     spider_db_handler *dbton_hdl = spider->dbton_handler[dbton_id];
     conn = spider->conns[roop_count];
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     if (dbton_hdl->need_lock_before_set_sql_for_exec(
       SPIDER_SQL_TYPE_DELETE_SQL))
     {
@@ -7280,6 +7385,12 @@ int spider_db_delete_all_rows(
     if ((error_num = dbton_hdl->set_sql_for_exec(
       SPIDER_SQL_TYPE_DELETE_SQL, roop_count)))
     {
+      if (dbton_hdl->need_lock_before_set_sql_for_exec(
+        SPIDER_SQL_TYPE_DELETE_SQL))
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+      }
       DBUG_RETURN(error_num);
     }
     if (!dbton_hdl->need_lock_before_set_sql_for_exec(
@@ -7289,6 +7400,8 @@ int spider_db_delete_all_rows(
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     }
     conn->need_mon = &spider->need_mons[roop_count];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, roop_count, spider->trx->thd,
@@ -7311,6 +7424,8 @@ int spider_db_delete_all_rows(
         /* retry */
         if ((error_num = spider_db_ping(spider, conn, roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -7339,6 +7454,8 @@ int spider_db_delete_all_rows(
         }
         if ((error_num = spider_db_set_names(spider, conn, roop_count)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -7373,6 +7490,8 @@ int spider_db_delete_all_rows(
           -1,
           &spider->need_mons[roop_count])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           error_num = spider_db_errorno(conn);
@@ -7399,6 +7518,8 @@ int spider_db_delete_all_rows(
           DBUG_RETURN(error_num);
         }
       } else {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -7426,6 +7547,8 @@ int spider_db_delete_all_rows(
         DBUG_RETURN(error_num);
       }
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -8807,7 +8930,14 @@ int spider_db_udf_direct_sql(
   c_thd->lex->sql_command = SQLCOM_INSERT;
 #endif
 
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (
     !(error_num = spider_db_udf_direct_sql_set_names(direct_sql, trx, conn)) &&
     !(error_num = spider_db_udf_direct_sql_select_db(direct_sql, conn))
@@ -8830,9 +8960,6 @@ int spider_db_udf_direct_sql(
 #endif
         DBUG_RETURN(error_num);
       }
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
     }
 #endif
     spider_conn_set_timeout_from_direct_sql(conn, thd, direct_sql);
@@ -8851,8 +8978,6 @@ int spider_db_udf_direct_sql(
       DBUG_PRINT("info",("spider conn=%p", conn));
       if (!direct_sql->table_count)
         roop_count = -1;
-      conn->mta_conn_mutex_lock_already = TRUE;
-      conn->mta_conn_mutex_unlock_later = TRUE;
       do {
         if (roop_count == direct_sql->table_count)
         {
@@ -9064,12 +9189,14 @@ int spider_db_udf_direct_sql(
         if (roop_count >= 0)
           roop_count++;
       } while (status == 0);
-      conn->mta_conn_mutex_lock_already = FALSE;
-      conn->mta_conn_mutex_unlock_later = FALSE;
-      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
+  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  pthread_mutex_unlock(&conn->mta_conn_mutex);
   if (need_trx_end && insert_start)
   {
     if (error_num)
@@ -9099,19 +9226,13 @@ int spider_db_udf_direct_sql_select_db(
   SPIDER_CONN *conn
 ) {
   int error_num, need_mon = 0;
-  bool tmp_mta_conn_mutex_lock_already;
   SPIDER_DB_CONN *db_conn = conn->db_conn;
   DBUG_ENTER("spider_db_udf_direct_sql_select_db");
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (direct_sql->access_mode == 0)
   {
 #endif
-    if (!conn->mta_conn_mutex_lock_already)
-    {
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      conn->need_mon = &need_mon;
-    }
     DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
     if (
       !conn->default_database.length() ||
@@ -9120,8 +9241,6 @@ int spider_db_udf_direct_sql_select_db(
       memcmp(direct_sql->tgt_default_db_name, conn->default_database.ptr(),
         direct_sql->tgt_default_db_name_length)
     ) {
-      tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-      conn->mta_conn_mutex_lock_already = TRUE;
       if (
         (
           spider_db_before_query(conn, &need_mon) ||
@@ -9135,7 +9254,6 @@ int spider_db_udf_direct_sql_select_db(
         )
           my_message(ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM,
             ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
-        conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
         DBUG_RETURN(error_num);
       }
       conn->default_database.length(0);
@@ -9145,12 +9263,6 @@ int spider_db_udf_direct_sql_select_db(
       conn->default_database.q_append(direct_sql->tgt_default_db_name,
         direct_sql->tgt_default_db_name_length + 1);
       conn->default_database.length(direct_sql->tgt_default_db_name_length);
-      conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-    }
-    if (!conn->mta_conn_mutex_unlock_later)
-    {
-      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   }
@@ -9164,25 +9276,17 @@ int spider_db_udf_direct_sql_set_names(
   SPIDER_CONN *conn
 ) {
   int error_num, need_mon = 0;
-  bool tmp_mta_conn_mutex_lock_already;
   DBUG_ENTER("spider_db_udf_direct_sql_set_names");
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   if (direct_sql->access_mode == 0)
   {
 #endif
-    if (!conn->mta_conn_mutex_lock_already)
-    {
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      conn->need_mon = &need_mon;
-    }
     DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
     if (
       !conn->access_charset ||
       trx->udf_access_charset->cset != conn->access_charset->cset
     ) {
-      tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-      conn->mta_conn_mutex_lock_already = TRUE;
       if (
         (
           spider_db_before_query(conn, &need_mon) ||
@@ -9197,17 +9301,10 @@ int spider_db_udf_direct_sql_set_names(
           my_message(ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM,
             ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
         }
-        conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
         DBUG_RETURN(error_num);
       }
-      conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
       conn->access_charset = trx->udf_access_charset;
     }
-    if (!conn->mta_conn_mutex_unlock_later)
-    {
-      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      pthread_mutex_unlock(&conn->mta_conn_mutex);
-    }
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   }
 #endif
@@ -9271,13 +9368,18 @@ int spider_db_udf_ping_table(
     spider.conn_link_idx = &tmp_conn_link_idx;
     spider.db_request_phase = &db_request_phase;
     spider.db_request_id = &db_request_id;
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_ping(&spider, conn, 0)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9293,6 +9395,8 @@ int spider_db_udf_ping_table(
         share->server_names[0]);
       DBUG_RETURN(ER_CONNECT_TO_FOREIGN_DATA_SOURCE);
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9336,13 +9440,18 @@ int spider_db_udf_ping_table(
         my_error(error_num, MYF(0));
         DBUG_RETURN(error_num);
       }
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       pthread_mutex_lock(&conn->mta_conn_mutex);
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
       conn->need_mon = &need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if ((error_num = spider_db_set_names(&spider, conn, 0)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9360,6 +9469,8 @@ int spider_db_udf_ping_table(
         -1,
         &need_mon)
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         error_num = spider_db_errorno(conn);
@@ -9368,6 +9479,8 @@ int spider_db_udf_ping_table(
         DBUG_PRINT("info",("spider error_num=%d", error_num));
         DBUG_RETURN(error_num);
       }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       spider_db_discard_result(&spider, 0, conn);
@@ -9553,13 +9666,18 @@ int spider_db_udf_ping_table_mon_next(
     DBUG_RETURN(error_num);
   }
 
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_ping(&spider, conn, 0)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9570,6 +9688,8 @@ int spider_db_udf_ping_table_mon_next(
   }
   if ((error_num = spider_db_set_names(&spider, conn, 0)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9584,6 +9704,8 @@ int spider_db_udf_ping_table_mon_next(
     -1,
     &need_mon)
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
@@ -9596,13 +9718,25 @@ int spider_db_udf_ping_table_mon_next(
   request_key.next = NULL;
   if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
-    if (error_num || (error_num = spider_db_errorno(conn)))
+    if (error_num)
+    {
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
+      DBUG_RETURN(error_num);
+    }
+    else if ((error_num = spider_db_errorno(conn)))
+    {
       DBUG_RETURN(error_num);
+    }
     my_error(HA_ERR_OUT_OF_MEM, MYF(0));
     DBUG_RETURN(HA_ERR_OUT_OF_MEM);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -9683,8 +9817,22 @@ int spider_db_udf_copy_tables(
         spider_conn_clear_queue_at_commit(tmp_conn);
         if (!tmp_conn->trx_start)
         {
+          pthread_mutex_assert_not_owner(&tmp_conn->mta_conn_mutex);
+          pthread_mutex_lock(&tmp_conn->mta_conn_mutex);
+          SPIDER_SET_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+          tmp_conn->need_mon = &tmp_spider->need_mons[0];
+          DBUG_ASSERT(!tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(!tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = TRUE;
+          tmp_conn->mta_conn_mutex_unlock_later = TRUE;
           if (spider_db_ping(tmp_spider, tmp_conn, 0))
           {
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+            tmp_conn->mta_conn_mutex_lock_already = FALSE;
+            tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+            SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
             my_error(ER_CONNECT_TO_FOREIGN_DATA_SOURCE, MYF(0),
               tmp_spider->share->server_names[0]);
             error_num = ER_CONNECT_TO_FOREIGN_DATA_SOURCE;
@@ -9694,8 +9842,21 @@ int spider_db_udf_copy_tables(
             (error_num = spider_db_set_names(tmp_spider, tmp_conn, 0)) ||
             (error_num = spider_db_start_transaction(tmp_conn,
               tmp_spider->need_mons))
-          )
+          ) {
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+            tmp_conn->mta_conn_mutex_lock_already = FALSE;
+            tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+            SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+            pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
             goto error_start_transaction;
+          }
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = FALSE;
+          tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
         }
       }
     } else {
@@ -9715,8 +9876,22 @@ int spider_db_udf_copy_tables(
       {
         tmp_spider = &spider[roop_count];
         tmp_conn = tmp_spider->conns[0];
+        pthread_mutex_assert_not_owner(&tmp_conn->mta_conn_mutex);
+        pthread_mutex_lock(&tmp_conn->mta_conn_mutex);
+        SPIDER_SET_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+        tmp_conn->need_mon = &tmp_spider->need_mons[0];
+        DBUG_ASSERT(!tmp_conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(!tmp_conn->mta_conn_mutex_unlock_later);
+        tmp_conn->mta_conn_mutex_lock_already = TRUE;
+        tmp_conn->mta_conn_mutex_unlock_later = TRUE;
         if (spider_db_ping(tmp_spider, tmp_conn, 0))
         {
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = FALSE;
+          tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
           my_error(ER_CONNECT_TO_FOREIGN_DATA_SOURCE, MYF(0),
             tmp_spider->share->server_names[0]);
           error_num = ER_CONNECT_TO_FOREIGN_DATA_SOURCE;
@@ -9729,11 +9904,23 @@ int spider_db_udf_copy_tables(
             (error_num = spider_db_lock_tables(tmp_spider, 0))
           )
         ) {
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = FALSE;
+          tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
           tmp_conn->table_lock = 0;
           if (error_num == HA_ERR_OUT_OF_MEM)
             my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
           goto error_lock_tables;
         }
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+        tmp_conn->mta_conn_mutex_lock_already = FALSE;
+        tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+        SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
         tmp_conn->table_lock = 1;
       }
     }
@@ -9741,11 +9928,23 @@ int spider_db_udf_copy_tables(
     tmp_conn = src_tbl_conn->conn;
     spider_conn_set_timeout_from_share(tmp_conn, 0,
       copy_tables->trx->thd, src_tbl_conn->share);
+    pthread_mutex_assert_not_owner(&tmp_conn->mta_conn_mutex);
+    pthread_mutex_lock(&tmp_conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+    tmp_conn->need_mon = &src_tbl_conn->need_mon;
+    DBUG_ASSERT(!tmp_conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!tmp_conn->mta_conn_mutex_unlock_later);
+    tmp_conn->mta_conn_mutex_lock_already = TRUE;
+    tmp_conn->mta_conn_mutex_unlock_later = TRUE;
     if (select_ct->exec_query(
       tmp_conn,
       -1,
       &src_tbl_conn->need_mon)
     ) {
+      DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+      tmp_conn->mta_conn_mutex_lock_already = FALSE;
+      tmp_conn->mta_conn_mutex_unlock_later = FALSE;
       error_num = spider_db_errorno(tmp_conn);
       if (error_num == ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM)
         my_message(ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM,
@@ -9774,6 +9973,10 @@ int spider_db_udf_copy_tables(
               my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
             result->free_result();
             delete result;
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+            tmp_conn->mta_conn_mutex_lock_already = FALSE;
+            tmp_conn->mta_conn_mutex_unlock_later = FALSE;
             SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
             pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
             goto error_db_query;
@@ -9789,6 +9992,10 @@ int spider_db_udf_copy_tables(
                 my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
               result->free_result();
               delete result;
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+              tmp_conn->mta_conn_mutex_lock_already = FALSE;
+              tmp_conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
               goto error_db_query;
@@ -9815,6 +10022,10 @@ int spider_db_udf_copy_tables(
                 my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
               result->free_result();
               delete result;
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+              tmp_conn->mta_conn_mutex_lock_already = FALSE;
+              tmp_conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
               goto error_db_query;
@@ -9832,6 +10043,10 @@ int spider_db_udf_copy_tables(
               my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
               result->free_result();
               delete result;
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+              DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+              tmp_conn->mta_conn_mutex_lock_already = FALSE;
+              tmp_conn->mta_conn_mutex_unlock_later = FALSE;
               SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
               pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
               error_num = ER_OUT_OF_RESOURCES;
@@ -9844,12 +10059,20 @@ int spider_db_udf_copy_tables(
             my_error(ER_OUT_OF_RESOURCES, MYF(0), HA_ERR_OUT_OF_MEM);
           result->free_result();
           delete result;
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = FALSE;
+          tmp_conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
           pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
           goto error_db_query;
         }
         result->free_result();
         delete result;
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+        tmp_conn->mta_conn_mutex_lock_already = FALSE;
+        tmp_conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
         for (dst_tbl_conn = copy_tables->table_conn[1]; dst_tbl_conn;
@@ -9870,6 +10093,12 @@ int spider_db_udf_copy_tables(
         }
         if (error_num)
         {
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+          tmp_conn->mta_conn_mutex_lock_already = FALSE;
+          tmp_conn->mta_conn_mutex_unlock_later = FALSE;
+          SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
+          pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
           if (error_num == ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM)
             my_message(ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM,
               ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
@@ -9877,6 +10106,10 @@ int spider_db_udf_copy_tables(
         }
         error_num = HA_ERR_END_OF_FILE;
         end_of_file = TRUE;
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
+        tmp_conn->mta_conn_mutex_lock_already = FALSE;
+        tmp_conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
         pthread_mutex_unlock(&tmp_conn->mta_conn_mutex);
       }
@@ -9919,9 +10152,12 @@ int spider_db_udf_copy_tables(
         {
           tmp_conn = dst_tbl_conn->conn;
           insert_ct = dst_tbl_conn->copy_table;
+          pthread_mutex_assert_not_owner(&tmp_conn->mta_conn_mutex);
           pthread_mutex_lock(&tmp_conn->mta_conn_mutex);
           SPIDER_SET_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
           tmp_conn->need_mon = &dst_tbl_conn->need_mon;
+          DBUG_ASSERT(!tmp_conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(!tmp_conn->mta_conn_mutex_unlock_later);
           tmp_conn->mta_conn_mutex_lock_already = TRUE;
           tmp_conn->mta_conn_mutex_unlock_later = TRUE;
           spider_conn_set_timeout_from_share(tmp_conn, 0,
@@ -9931,6 +10167,8 @@ int spider_db_udf_copy_tables(
             -1,
             &dst_tbl_conn->need_mon)
           ) {
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
             tmp_conn->mta_conn_mutex_lock_already = FALSE;
             tmp_conn->mta_conn_mutex_unlock_later = FALSE;
             error_num = spider_db_errorno(tmp_conn);
@@ -9939,6 +10177,8 @@ int spider_db_udf_copy_tables(
                 ER_SPIDER_REMOTE_SERVER_GONE_AWAY_STR, MYF(0));
             goto error_db_query;
           } else {
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_lock_already);
+            DBUG_ASSERT(tmp_conn->mta_conn_mutex_unlock_later);
             tmp_conn->mta_conn_mutex_lock_already = FALSE;
             tmp_conn->mta_conn_mutex_unlock_later = FALSE;
             SPIDER_CLEAR_FILE_POS(&tmp_conn->mta_conn_mutex_file_pos);
@@ -10079,8 +10319,6 @@ int spider_db_open_handler(
   int link_idx
 ) {
   int error_num;
-  bool tmp_mta_conn_mutex_lock_already;
-  bool tmp_mta_conn_mutex_unlock_later;
   SPIDER_SHARE *share = spider->share;
   uint *handler_id_ptr =
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
@@ -10095,16 +10333,14 @@ int spider_db_open_handler(
     ;
   spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
   DBUG_ENTER("spider_db_open_handler");
-  if (!conn->mta_conn_mutex_lock_already)
-  {
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = &spider->need_mons[link_idx];
-  }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
   DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
-  tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
-  tmp_mta_conn_mutex_unlock_later = conn->mta_conn_mutex_unlock_later;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if (!spider->handler_opened(link_idx, conn->conn_kind))
     *handler_id_ptr = conn->opened_handlers;
@@ -10153,11 +10389,6 @@ int spider_db_open_handler(
       {
         my_printf_error(ER_SPIDER_HS_NUM, ER_SPIDER_HS_STR, MYF(0),
           conn->db_conn->get_errno(), conn->db_conn->get_error());
-        if (!conn->mta_conn_mutex_unlock_later)
-        {
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-        }
         spider->need_mons[link_idx] = ER_SPIDER_HS_NUM;
         error_num = ER_SPIDER_HS_NUM;
         goto error;
@@ -10293,23 +10524,21 @@ int spider_db_open_handler(
   }
   DBUG_PRINT("info",("spider conn=%p", conn));
   DBUG_PRINT("info",("spider opened_handlers=%u", conn->opened_handlers));
-  conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-  conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
-  if (!tmp_mta_conn_mutex_unlock_later)
-  {
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
+  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
 
 error:
-  conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-  conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
-  if (!tmp_mta_conn_mutex_unlock_later)
-  {
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
+  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(error_num);
 }
 
@@ -10359,6 +10588,7 @@ int spider_db_bulk_open_handler(
     }
 
     bool tmp_mta_conn_mutex_unlock_later;
+    pthread_mutex_assert_owner(&conn->mta_conn_mutex);
     tmp_mta_conn_mutex_unlock_later = conn->mta_conn_mutex_unlock_later;
     conn->mta_conn_mutex_unlock_later = TRUE;
     SPIDER_DB_RESULT *result;
@@ -10397,24 +10627,19 @@ int spider_db_close_handler(
   uint tgt_conn_kind
 ) {
   int error_num;
-  bool tmp_mta_conn_mutex_lock_already;
-  bool tmp_mta_conn_mutex_unlock_later;
   spider_db_handler *dbton_hdl = spider->dbton_handler[conn->dbton_id];
   DBUG_ENTER("spider_db_close_handler");
   DBUG_PRINT("info",("spider conn=%p", conn));
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider->handler_opened(link_idx, tgt_conn_kind))
   {
-    if (!conn->mta_conn_mutex_lock_already)
-    {
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      conn->need_mon = &spider->need_mons[link_idx];
-    }
-    DBUG_ASSERT(conn->mta_conn_mutex_file_pos.file_name);
-    tmp_mta_conn_mutex_lock_already = conn->mta_conn_mutex_lock_already;
-    conn->mta_conn_mutex_lock_already = TRUE;
-    tmp_mta_conn_mutex_unlock_later = conn->mta_conn_mutex_unlock_later;
-    conn->mta_conn_mutex_unlock_later = TRUE;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
     if (conn->conn_kind == SPIDER_CONN_KIND_MYSQL)
     {
@@ -10422,7 +10647,15 @@ int spider_db_close_handler(
       dbton_hdl->reset_sql(SPIDER_SQL_TYPE_HANDLER);
       if ((error_num = dbton_hdl->append_close_handler_part(
         SPIDER_SQL_TYPE_HANDLER, link_idx)))
+      {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
         DBUG_RETURN(error_num);
+      }
 
       spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
         spider->share);
@@ -10448,24 +10681,22 @@ int spider_db_close_handler(
       goto error;
     conn->opened_handlers--;
     DBUG_PRINT("info",("spider opened_handlers=%u", conn->opened_handlers));
-    conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-    conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
-    if (!tmp_mta_conn_mutex_unlock_later)
-    {
-      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-      pthread_mutex_unlock(&conn->mta_conn_mutex);
-    }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
+  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
 
 error:
-  conn->mta_conn_mutex_lock_already = tmp_mta_conn_mutex_lock_already;
-  conn->mta_conn_mutex_unlock_later = tmp_mta_conn_mutex_unlock_later;
-  if (!tmp_mta_conn_mutex_unlock_later)
-  {
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
+  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(error_num);
 }
 
@@ -10502,3 +10733,4 @@ bool spider_db_conn_is_network_error(
   }
   DBUG_RETURN(FALSE);
 }
+
diff --git a/storage/spider/spd_db_mysql.cc b/storage/spider/spd_db_mysql.cc
index 2be4c810c06..9ed29d015b3 100644
--- a/storage/spider/spd_db_mysql.cc
+++ b/storage/spider/spd_db_mysql.cc
@@ -1844,10 +1844,6 @@ void spider_db_mysql::print_warnings(
     if (!(db_conn->server_status & SERVER_MORE_RESULTS_EXISTS))
 #endif
     {
-/*
-      pthread_mutex_lock(&conn->mta_conn_mutex);
-      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-*/
       if (
         spider_param_dry_access() ||
         !mysql_real_query(db_conn, SPIDER_SQL_SHOW_WARNINGS_STR,
@@ -1865,18 +1861,10 @@ void spider_db_mysql::print_warnings(
           {
             if (res)
               mysql_free_result(res);
-/*
-            SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-            pthread_mutex_unlock(&conn->mta_conn_mutex);
-*/
             DBUG_VOID_RETURN;
           }
           /* no record is ok */
         }
-/*
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-*/
         num_fields = mysql_num_fields(res);
         if (num_fields != 3)
         {
@@ -1895,11 +1883,6 @@ void spider_db_mysql::print_warnings(
         }
         if (res)
           mysql_free_result(res);
-      } else {
-/*
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-*/
       }
     }
   }
@@ -2039,14 +2022,31 @@ int spider_db_mysql::consistent_snapshot(
 ) {
   DBUG_ENTER("spider_db_mysql::consistent_snapshot");
   DBUG_PRINT("info",("spider this=%p", this));
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     SPIDER_SQL_START_CONSISTENT_SNAPSHOT_STR,
     SPIDER_SQL_START_CONSISTENT_SNAPSHOT_LEN,
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2064,16 +2064,18 @@ int spider_db_mysql::start_transaction(
 ) {
   DBUG_ENTER("spider_db_mysql::start_transaction");
   DBUG_PRINT("info",("spider this=%p", this));
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   if (spider_db_query(
     conn,
     SPIDER_SQL_START_TRANSACTION_STR,
     SPIDER_SQL_START_TRANSACTION_LEN,
     -1,
     need_mon)
-  )
+  ) {
     DBUG_RETURN(spider_db_errorno(conn));
-  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-  pthread_mutex_unlock(&conn->mta_conn_mutex);
+  }
   DBUG_RETURN(0);
 }
 
@@ -2082,14 +2084,31 @@ int spider_db_mysql::commit(
 ) {
   DBUG_ENTER("spider_db_mysql::commit");
   DBUG_PRINT("info",("spider this=%p", this));
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     SPIDER_SQL_COMMIT_STR,
     SPIDER_SQL_COMMIT_LEN,
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2102,6 +2121,13 @@ int spider_db_mysql::rollback(
   int error_num;
   DBUG_ENTER("spider_db_mysql::rollback");
   DBUG_PRINT("info",("spider this=%p", this));
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
@@ -2118,12 +2144,18 @@ int spider_db_mysql::rollback(
     )
       conn->thd->clear_error();
     else {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       DBUG_RETURN(error_num);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
@@ -2160,14 +2192,31 @@ int spider_db_mysql::xa_end(
   sql_str.length(0);
   sql_str.q_append(SPIDER_SQL_XA_END_STR, SPIDER_SQL_XA_END_LEN);
   spider_db_append_xid_str(&sql_str, xid);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     sql_str.ptr(),
     sql_str.length(),
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2186,14 +2235,31 @@ int spider_db_mysql::xa_prepare(
   sql_str.length(0);
   sql_str.q_append(SPIDER_SQL_XA_PREPARE_STR, SPIDER_SQL_XA_PREPARE_LEN);
   spider_db_append_xid_str(&sql_str, xid);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     sql_str.ptr(),
     sql_str.length(),
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2212,14 +2278,31 @@ int spider_db_mysql::xa_commit(
   sql_str.length(0);
   sql_str.q_append(SPIDER_SQL_XA_COMMIT_STR, SPIDER_SQL_XA_COMMIT_LEN);
   spider_db_append_xid_str(&sql_str, xid);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     sql_str.ptr(),
     sql_str.length(),
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2238,14 +2321,31 @@ int spider_db_mysql::xa_rollback(
   sql_str.length(0);
   sql_str.q_append(SPIDER_SQL_XA_ROLLBACK_STR, SPIDER_SQL_XA_ROLLBACK_LEN);
   spider_db_append_xid_str(&sql_str, xid);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     sql_str.ptr(),
     sql_str.length(),
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -2267,50 +2367,118 @@ int spider_db_mysql::set_trx_isolation(
   switch (trx_isolation)
   {
     case ISO_READ_UNCOMMITTED:
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_READ_UNCOMMITTED_STR,
         SPIDER_SQL_ISO_READ_UNCOMMITTED_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
     case ISO_READ_COMMITTED:
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_READ_COMMITTED_STR,
         SPIDER_SQL_ISO_READ_COMMITTED_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
     case ISO_REPEATABLE_READ:
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_REPEATABLE_READ_STR,
         SPIDER_SQL_ISO_REPEATABLE_READ_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
     case ISO_SERIALIZABLE:
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_SERIALIZABLE_STR,
         SPIDER_SQL_ISO_SERIALIZABLE_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
@@ -2335,25 +2503,59 @@ int spider_db_mysql::set_autocommit(
   DBUG_PRINT("info",("spider this=%p", this));
   if (autocommit)
   {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_AUTOCOMMIT_ON_STR,
       SPIDER_SQL_AUTOCOMMIT_ON_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_AUTOCOMMIT_OFF_STR,
       SPIDER_SQL_AUTOCOMMIT_OFF_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   }
@@ -2375,25 +2577,59 @@ int spider_db_mysql::set_sql_log_off(
   DBUG_PRINT("info",("spider this=%p", this));
   if (sql_log_off)
   {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_SQL_LOG_ON_STR,
       SPIDER_SQL_SQL_LOG_ON_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_SQL_LOG_OFF_STR,
       SPIDER_SQL_SQL_LOG_OFF_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   }
@@ -2424,14 +2660,31 @@ int spider_db_mysql::set_time_zone(
   sql_str.q_append(SPIDER_SQL_TIME_ZONE_STR, SPIDER_SQL_TIME_ZONE_LEN);
   sql_str.q_append(tz_str->ptr(), tz_str->length());
   sql_str.q_append(SPIDER_SQL_VALUE_QUOTE_STR, SPIDER_SQL_VALUE_QUOTE_LEN);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = need_mon;
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     sql_str.ptr(),
     sql_str.length(),
     -1,
     need_mon)
-  )
+  ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     DBUG_RETURN(spider_db_errorno(conn));
+  }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -4973,6 +5226,14 @@ int spider_mysql_share::discover_table_structure(
     ) {
       DBUG_RETURN(error_num);
     }
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = &need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (!conn->disable_reconnect)
     {
       ha_spider tmp_spider;
@@ -4985,14 +5246,15 @@ int spider_mysql_share::discover_table_structure(
       if ((error_num = spider_db_ping(&tmp_spider, conn, 0)))
       {
         DBUG_PRINT("info",("spider spider_db_ping error"));
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
         continue;
       }
     }
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = &need_mon;
-    conn->mta_conn_mutex_lock_already = TRUE;
-    conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, roop_count, trx->thd,
       spider_share);
     if (
@@ -5009,6 +5271,8 @@ int spider_mysql_share::discover_table_structure(
       )
     ) {
       DBUG_PRINT("info",("spider spider_get_trx error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5028,6 +5292,8 @@ int spider_mysql_share::discover_table_structure(
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
         DBUG_PRINT("info",("spider column store error"));
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5036,6 +5302,8 @@ int spider_mysql_share::discover_table_structure(
       }
       /* no record */
       DBUG_PRINT("info",("spider column no record error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5048,6 +5316,8 @@ int spider_mysql_share::discover_table_structure(
       DBUG_PRINT("info",("spider column fetch error"));
       res->free_result();
       delete res;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5064,6 +5334,8 @@ int spider_mysql_share::discover_table_structure(
     if (conn->db_conn->next_result())
     {
       DBUG_PRINT("info",("spider single result error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5076,6 +5348,8 @@ int spider_mysql_share::discover_table_structure(
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
         DBUG_PRINT("info",("spider index store error"));
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5084,6 +5358,8 @@ int spider_mysql_share::discover_table_structure(
       }
       /* no record */
       DBUG_PRINT("info",("spider index no record error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5096,6 +5372,8 @@ int spider_mysql_share::discover_table_structure(
       DBUG_PRINT("info",("spider index fetch error"));
       res->free_result();
       delete res;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5107,6 +5385,8 @@ int spider_mysql_share::discover_table_structure(
     if (conn->db_conn->next_result())
     {
       DBUG_PRINT("info",("spider dual result error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5119,6 +5399,8 @@ int spider_mysql_share::discover_table_structure(
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
         DBUG_PRINT("info",("spider table store error"));
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5127,6 +5409,8 @@ int spider_mysql_share::discover_table_structure(
       }
       /* no record */
       DBUG_PRINT("info",("spider table no record error"));
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5139,6 +5423,8 @@ int spider_mysql_share::discover_table_structure(
       DBUG_PRINT("info",("spider table fetch error"));
       res->free_result();
       delete res;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5147,6 +5433,8 @@ int spider_mysql_share::discover_table_structure(
     }
     res->free_result();
     delete res;
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10347,9 +10635,12 @@ int spider_mysql_handler::show_table_status(
 
   if (sts_mode == 1)
   {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     conn->disable_connect_retry = TRUE;
@@ -10375,6 +10666,8 @@ int spider_mysql_handler::show_table_status(
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10384,6 +10677,8 @@ int spider_mysql_handler::show_table_status(
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10400,12 +10695,16 @@ int spider_mysql_handler::show_table_status(
           &spider->need_mons[link_idx])
         ) {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
         conn->disable_connect_retry = FALSE;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10422,6 +10721,8 @@ int spider_mysql_handler::show_table_status(
     if (spider_param_dry_access())
     {
       conn->disable_connect_retry = FALSE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10431,9 +10732,17 @@ int spider_mysql_handler::show_table_status(
     if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
     {
       conn->disable_connect_retry = FALSE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
-      if (error_num || (error_num = spider_db_errorno(conn)))
+      if (error_num)
+      {
+        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+        pthread_mutex_unlock(&conn->mta_conn_mutex);
+        DBUG_RETURN(error_num);
+      }
+      else if ((error_num = spider_db_errorno(conn)))
         DBUG_RETURN(error_num);
       else
       {
@@ -10446,6 +10755,8 @@ int spider_mysql_handler::show_table_status(
       }
     }
     conn->disable_connect_retry = FALSE;
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10488,9 +10799,12 @@ int spider_mysql_handler::show_table_status(
       DBUG_RETURN(error_num);
     }
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     conn->disable_connect_retry = TRUE;
@@ -10516,6 +10830,8 @@ int spider_mysql_handler::show_table_status(
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10525,6 +10841,8 @@ int spider_mysql_handler::show_table_status(
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10541,12 +10859,16 @@ int spider_mysql_handler::show_table_status(
           &spider->need_mons[link_idx])
         ) {
           conn->disable_connect_retry = FALSE;
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
         conn->disable_connect_retry = FALSE;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10563,6 +10885,8 @@ int spider_mysql_handler::show_table_status(
     if (spider_param_dry_access())
     {
       conn->disable_connect_retry = FALSE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10572,6 +10896,8 @@ int spider_mysql_handler::show_table_status(
     if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
     {
       conn->disable_connect_retry = FALSE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       if (error_num || (error_num = spider_db_errorno(conn)))
@@ -10580,6 +10906,8 @@ int spider_mysql_handler::show_table_status(
         DBUG_RETURN(ER_QUERY_ON_FOREIGN_DATA_SOURCE);
     }
     conn->disable_connect_retry = FALSE;
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10664,9 +10992,12 @@ int spider_mysql_handler::show_index(
   DBUG_PRINT("info",("spider crd_mode=%d", crd_mode));
   if (crd_mode == 1)
   {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10690,6 +11021,8 @@ int spider_mysql_handler::show_index(
         /* retry */
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10698,6 +11031,8 @@ int spider_mysql_handler::show_index(
         }
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10713,11 +11048,15 @@ int spider_mysql_handler::show_index(
           -1,
           &spider->need_mons[link_idx])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10735,6 +11074,8 @@ int spider_mysql_handler::show_index(
     {
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10743,6 +11084,8 @@ int spider_mysql_handler::show_index(
       }
       /* no record is ok */
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10797,9 +11140,12 @@ int spider_mysql_handler::show_index(
       DBUG_RETURN(error_num);
     }
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10823,6 +11169,8 @@ int spider_mysql_handler::show_index(
         /* retry */
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10831,6 +11179,8 @@ int spider_mysql_handler::show_index(
         }
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10846,11 +11196,15 @@ int spider_mysql_handler::show_index(
           -1,
           &spider->need_mons[link_idx])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10868,6 +11222,8 @@ int spider_mysql_handler::show_index(
     {
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10876,6 +11232,8 @@ int spider_mysql_handler::show_index(
       }
       /* no record is ok */
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10942,9 +11300,12 @@ int spider_mysql_handler::show_records(
   SPIDER_SHARE *share = spider->share;
   uint pos = spider->conn_link_idx[link_idx];
   DBUG_ENTER("spider_mysql_handler::show_records");
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10968,6 +11329,8 @@ int spider_mysql_handler::show_records(
       /* retry */
       if ((error_num = spider_db_ping(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10977,6 +11340,8 @@ int spider_mysql_handler::show_records(
       }
       if ((error_num = spider_db_set_names(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10993,12 +11358,16 @@ int spider_mysql_handler::show_records(
         -1,
         &spider->need_mons[link_idx])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_PRINT("info", ("spider error_num=%d 3", error_num));
         DBUG_RETURN(spider_db_errorno(conn));
       }
     } else {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11015,18 +11384,29 @@ int spider_mysql_handler::show_records(
   request_key.next = NULL;
   if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
-    if (error_num || (error_num = spider_db_errorno(conn)))
+    if (error_num)
     {
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       DBUG_PRINT("info", ("spider error_num=%d 5", error_num));
       DBUG_RETURN(error_num);
+    }
+    else if ((error_num = spider_db_errorno(conn)))
+    {
+      DBUG_PRINT("info", ("spider error_num=%d 6", error_num));
+      DBUG_RETURN(error_num);
     } else {
-      DBUG_PRINT("info", ("spider error_num=%d 6",
+      DBUG_PRINT("info", ("spider error_num=%d 7",
         ER_QUERY_ON_FOREIGN_DATA_SOURCE));
       DBUG_RETURN(ER_QUERY_ON_FOREIGN_DATA_SOURCE);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11076,9 +11456,12 @@ ha_rows spider_mysql_handler::explain_select(
     DBUG_RETURN(HA_POS_ERROR);
   }
 
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -11104,6 +11487,8 @@ ha_rows spider_mysql_handler::explain_select(
       {
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11114,6 +11499,8 @@ ha_rows spider_mysql_handler::explain_select(
       {
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11132,6 +11519,8 @@ ha_rows spider_mysql_handler::explain_select(
         error_num = spider_db_errorno(conn);
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11141,6 +11530,8 @@ ha_rows spider_mysql_handler::explain_select(
     } else {
       if (spider->check_error_mode(error_num))
         my_errno = error_num;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11160,6 +11551,8 @@ ha_rows spider_mysql_handler::explain_select(
     {
       if (spider->check_error_mode(error_num))
         my_errno = error_num;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11167,6 +11560,8 @@ ha_rows spider_mysql_handler::explain_select(
       DBUG_RETURN(HA_POS_ERROR);
     } else {
       my_errno = ER_QUERY_ON_FOREIGN_DATA_SOURCE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11174,6 +11569,8 @@ ha_rows spider_mysql_handler::explain_select(
       DBUG_RETURN(HA_POS_ERROR);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11206,13 +11603,18 @@ int spider_mysql_handler::lock_tables(
   }
   if (str->length())
   {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_set_names(spider, conn, link_idx)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11228,10 +11630,14 @@ int spider_mysql_handler::lock_tables(
       -1,
       &spider->need_mons[link_idx])
     ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11266,14 +11672,31 @@ int spider_mysql_handler::unlock_tables(
     {
       spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
         spider->share);
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = &spider->need_mons[link_idx];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         str->ptr(),
         str->length(),
         -1,
         &spider->need_mons[link_idx])
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
     }
@@ -11296,13 +11719,18 @@ int spider_mysql_handler::disable_keys(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11318,11 +11746,15 @@ int spider_mysql_handler::disable_keys(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11345,13 +11777,18 @@ int spider_mysql_handler::enable_keys(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11367,11 +11804,15 @@ int spider_mysql_handler::enable_keys(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11395,13 +11836,18 @@ int spider_mysql_handler::check_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11417,11 +11863,15 @@ int spider_mysql_handler::check_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11445,13 +11895,18 @@ int spider_mysql_handler::repair_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11467,11 +11922,15 @@ int spider_mysql_handler::repair_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11494,13 +11953,18 @@ int spider_mysql_handler::analyze_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11516,11 +11980,15 @@ int spider_mysql_handler::analyze_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11543,13 +12011,18 @@ int spider_mysql_handler::optimize_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11565,11 +12038,15 @@ int spider_mysql_handler::optimize_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11595,6 +12072,14 @@ int spider_mysql_handler::flush_tables(
   }
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
     share);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     str->ptr(),
@@ -11602,9 +12087,17 @@ int spider_mysql_handler::flush_tables(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -11620,6 +12113,14 @@ int spider_mysql_handler::flush_logs(
   DBUG_PRINT("info",("spider this=%p", this));
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
     share);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     SPIDER_SQL_FLUSH_LOGS_STR,
@@ -11627,9 +12128,17 @@ int spider_mysql_handler::flush_logs(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
diff --git a/storage/spider/spd_db_oracle.cc b/storage/spider/spd_db_oracle.cc
index 281e3188067..d5d41f4a994 100644
--- a/storage/spider/spd_db_oracle.cc
+++ b/storage/spider/spd_db_oracle.cc
@@ -1780,16 +1780,18 @@ int spider_db_oracle::start_transaction(
     }
     DBUG_RETURN(set_trx_isolation(conn->trx_isolation, need_mon));
   }
+  pthread_mutex_assert_owner(&conn->mta_conn_mutex);
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   if (spider_db_query(
     conn,
     SPIDER_SQL_START_TRANSACTION_STR,
     SPIDER_SQL_START_TRANSACTION_LEN,
     -1,
     need_mon)
-  )
+  ) {
     DBUG_RETURN(spider_db_errorno(conn));
-  SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-  pthread_mutex_unlock(&conn->mta_conn_mutex);
+  }
   DBUG_RETURN(0);
 }
 
@@ -1978,14 +1980,31 @@ int spider_db_oracle::set_trx_isolation(
         DBUG_RETURN(exec_query(SPIDER_SQL_ISO_READ_COMMITTED_STR,
           SPIDER_SQL_ISO_READ_COMMITTED_LEN, -1));
       }
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_READ_COMMITTED_STR,
         SPIDER_SQL_ISO_READ_COMMITTED_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
@@ -1996,14 +2015,31 @@ int spider_db_oracle::set_trx_isolation(
         DBUG_RETURN(exec_query(SPIDER_SQL_ISO_SERIALIZABLE_STR,
           SPIDER_SQL_ISO_SERIALIZABLE_LEN, -1));
       }
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+      pthread_mutex_lock(&conn->mta_conn_mutex);
+      SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      conn->need_mon = need_mon;
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = TRUE;
+      conn->mta_conn_mutex_unlock_later = TRUE;
       if (spider_db_query(
         conn,
         SPIDER_SQL_ISO_SERIALIZABLE_STR,
         SPIDER_SQL_ISO_SERIALIZABLE_LEN,
         -1,
         need_mon)
-      )
+      ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+        conn->mta_conn_mutex_lock_already = FALSE;
+        conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
+      }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
       pthread_mutex_unlock(&conn->mta_conn_mutex);
       break;
@@ -2033,14 +2069,31 @@ int spider_db_oracle::set_autocommit(
       DBUG_RETURN(exec_query(SPIDER_SQL_AUTOCOMMIT_ON_STR,
         SPIDER_SQL_AUTOCOMMIT_ON_LEN, -1));
     }
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_AUTOCOMMIT_ON_STR,
       SPIDER_SQL_AUTOCOMMIT_ON_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   } else {
@@ -2049,14 +2102,31 @@ int spider_db_oracle::set_autocommit(
       DBUG_RETURN(exec_query(SPIDER_SQL_AUTOCOMMIT_OFF_STR,
         SPIDER_SQL_AUTOCOMMIT_OFF_LEN, -1));
     }
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+    pthread_mutex_lock(&conn->mta_conn_mutex);
+    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    conn->need_mon = need_mon;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = TRUE;
+    conn->mta_conn_mutex_unlock_later = TRUE;
     if (spider_db_query(
       conn,
       SPIDER_SQL_AUTOCOMMIT_OFF_STR,
       SPIDER_SQL_AUTOCOMMIT_OFF_LEN,
       -1,
       need_mon)
-    )
+    ) {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+      conn->mta_conn_mutex_lock_already = FALSE;
+      conn->mta_conn_mutex_unlock_later = FALSE;
       DBUG_RETURN(spider_db_errorno(conn));
+    }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
     pthread_mutex_unlock(&conn->mta_conn_mutex);
   }
@@ -10449,112 +10519,6 @@ int spider_oracle_handler::show_table_status(
 
   if (sts_mode == 1)
   {
-/*
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = &spider->need_mons[link_idx];
-    conn->mta_conn_mutex_lock_already = TRUE;
-    conn->mta_conn_mutex_unlock_later = TRUE;
-    spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
-      share);
-    if (
-      (error_num = spider_db_set_names(spider, conn, link_idx)) ||
-      (
-        spider_db_query(
-          conn,
-          oracle_share->show_table_status[0 + pos].ptr(),
-          oracle_share->show_table_status[0 + pos].length(),
-          -1,
-          &spider->need_mons[link_idx]) &&
-        (error_num = spider_db_errorno(conn))
-      )
-    ) {
-      if (
-        error_num == ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM &&
-        !conn->disable_reconnect
-      ) {
-*/
-        /* retry */
-/*
-        if ((error_num = spider_db_ping(spider, conn, link_idx)))
-        {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-          DBUG_RETURN(error_num);
-        }
-        if ((error_num = spider_db_set_names(spider, conn, link_idx)))
-        {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-          DBUG_RETURN(error_num);
-        }
-        spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
-          share);
-        if (spider_db_query(
-          conn,
-          oracle_share->show_table_status[0 + pos].ptr(),
-          oracle_share->show_table_status[0 + pos].length(),
-          -1,
-          &spider->need_mons[link_idx])
-        ) {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          DBUG_RETURN(spider_db_errorno(conn));
-        }
-      } else {
-        conn->mta_conn_mutex_lock_already = FALSE;
-        conn->mta_conn_mutex_unlock_later = FALSE;
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-        DBUG_RETURN(error_num);
-      }
-    }
-    st_spider_db_request_key request_key;
-    request_key.spider_thread_id = spider->trx->spider_thread_id;
-    request_key.query_id = spider->trx->thd->query_id;
-    request_key.handler = spider;
-    request_key.request_id = 1;
-    request_key.next = NULL;
-    if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
-    {
-      conn->mta_conn_mutex_lock_already = FALSE;
-      conn->mta_conn_mutex_unlock_later = FALSE;
-      if (error_num || (error_num = spider_db_errorno(conn)))
-        DBUG_RETURN(error_num);
-      else {
-        my_printf_error(ER_SPIDER_REMOTE_TABLE_NOT_FOUND_NUM,
-          ER_SPIDER_REMOTE_TABLE_NOT_FOUND_STR, MYF(0),
-          oracle_share->db_names_str[spider->conn_link_idx[link_idx]].ptr(),
-          oracle_share->table_names_str[spider->conn_link_idx[
-            link_idx]].ptr());
-        DBUG_RETURN(ER_SPIDER_REMOTE_TABLE_NOT_FOUND_NUM);
-      }
-    }
-    conn->mta_conn_mutex_lock_already = FALSE;
-    conn->mta_conn_mutex_unlock_later = FALSE;
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-    error_num = res->fetch_table_status(
-      sts_mode,
-      share->records,
-      share->mean_rec_length,
-      share->data_file_length,
-      share->max_data_file_length,
-      share->index_file_length,
-      auto_increment_value,
-      share->create_time,
-      share->update_time,
-      share->check_time
-    );
-    res->free_result();
-    delete res;
-    if (error_num)
-      DBUG_RETURN(error_num);
-*/
     if (!share->records)
       share->records = 10000;
     share->mean_rec_length = 65535;
@@ -10565,9 +10529,12 @@ int spider_oracle_handler::show_table_status(
     share->update_time = (time_t) 0;
     share->check_time = (time_t) 0;
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10591,6 +10558,8 @@ int spider_oracle_handler::show_table_status(
         /* retry */
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10599,6 +10568,8 @@ int spider_oracle_handler::show_table_status(
         }
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10614,11 +10585,15 @@ int spider_oracle_handler::show_table_status(
           -1,
           &spider->need_mons[link_idx])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10634,6 +10609,8 @@ int spider_oracle_handler::show_table_status(
     request_key.next = NULL;
     if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       if (error_num || (error_num = spider_db_errorno(conn)))
@@ -10641,6 +10618,8 @@ int spider_oracle_handler::show_table_status(
       else
         DBUG_RETURN(ER_QUERY_ON_FOREIGN_DATA_SOURCE);
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10695,105 +10674,6 @@ int spider_oracle_handler::show_index(
   DBUG_PRINT("info",("spider crd_mode=%d", crd_mode));
   if (crd_mode == 1)
   {
-/*
-    pthread_mutex_lock(&conn->mta_conn_mutex);
-    SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    conn->need_mon = &spider->need_mons[link_idx];
-    conn->mta_conn_mutex_lock_already = TRUE;
-    conn->mta_conn_mutex_unlock_later = TRUE;
-    spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
-      share);
-    if (
-      (error_num = spider_db_set_names(spider, conn, link_idx)) ||
-      (
-        spider_db_query(
-          conn,
-          oracle_share->show_index[0 + pos].ptr(),
-          oracle_share->show_index[0 + pos].length(),
-          -1,
-          &spider->need_mons[link_idx]) &&
-        (error_num = spider_db_errorno(conn))
-      )
-    ) {
-      if (
-        error_num == ER_SPIDER_REMOTE_SERVER_GONE_AWAY_NUM &&
-        !conn->disable_reconnect
-      ) {
-*/
-        /* retry */
-/*
-        if ((error_num = spider_db_ping(spider, conn, link_idx)))
-        {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-          DBUG_RETURN(error_num);
-        }
-        if ((error_num = spider_db_set_names(spider, conn, link_idx)))
-        {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-          pthread_mutex_unlock(&conn->mta_conn_mutex);
-          DBUG_RETURN(error_num);
-        }
-        spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
-          share);
-        if (spider_db_query(
-          conn,
-          oracle_share->show_index[0 + pos].ptr(),
-          oracle_share->show_index[0 + pos].length(),
-          -1,
-          &spider->need_mons[link_idx])
-        ) {
-          conn->mta_conn_mutex_lock_already = FALSE;
-          conn->mta_conn_mutex_unlock_later = FALSE;
-          DBUG_RETURN(spider_db_errorno(conn));
-        }
-      } else {
-        conn->mta_conn_mutex_lock_already = FALSE;
-        conn->mta_conn_mutex_unlock_later = FALSE;
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-        DBUG_RETURN(error_num);
-      }
-    }
-    st_spider_db_request_key request_key;
-    request_key.spider_thread_id = spider->trx->spider_thread_id;
-    request_key.query_id = spider->trx->thd->query_id;
-    request_key.handler = spider;
-    request_key.request_id = 1;
-    request_key.next = NULL;
-    if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
-    {
-      if (error_num || (error_num = spider_db_errorno(conn)))
-      {
-        conn->mta_conn_mutex_lock_already = FALSE;
-        conn->mta_conn_mutex_unlock_later = FALSE;
-        SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-        pthread_mutex_unlock(&conn->mta_conn_mutex);
-        DBUG_RETURN(error_num);
-      }
-*/
-      /* no record is ok */
-/*
-    }
-    conn->mta_conn_mutex_lock_already = FALSE;
-    conn->mta_conn_mutex_unlock_later = FALSE;
-    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
-    pthread_mutex_unlock(&conn->mta_conn_mutex);
-    if (res)
-    {
-      error_num = res->fetch_table_cardinality(
-        crd_mode,
-        table,
-        share->cardinality,
-        share->cardinality_upd,
-        share->bitmap_size
-      );
-    }
-*/
     for (roop_count = 0, tmp_cardinality = share->cardinality;
       roop_count < (int) table->s->fields;
       roop_count++, tmp_cardinality++)
@@ -10805,19 +10685,13 @@ int spider_oracle_handler::show_index(
         *tmp_cardinality = 1;
       }
     }
-/*
-    if (res)
-    {
-      res->free_result();
-      delete res;
-    }
-    if (error_num)
-      DBUG_RETURN(error_num);
-*/
   } else {
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &spider->need_mons[link_idx];
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10841,6 +10715,8 @@ int spider_oracle_handler::show_index(
         /* retry */
         if ((error_num = spider_db_ping(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10849,6 +10725,8 @@ int spider_oracle_handler::show_index(
         }
         if ((error_num = spider_db_set_names(spider, conn, link_idx)))
         {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10864,11 +10742,15 @@ int spider_oracle_handler::show_index(
           -1,
           &spider->need_mons[link_idx])
         ) {
+          DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+          DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
           conn->mta_conn_mutex_lock_already = FALSE;
           conn->mta_conn_mutex_unlock_later = FALSE;
           DBUG_RETURN(spider_db_errorno(conn));
         }
       } else {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10886,6 +10768,8 @@ int spider_oracle_handler::show_index(
     {
       if (error_num || (error_num = spider_db_errorno(conn)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10894,6 +10778,8 @@ int spider_oracle_handler::show_index(
       }
       /* no record is ok */
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10939,9 +10825,12 @@ int spider_oracle_handler::show_records(
   SPIDER_SHARE *share = spider->share;
   uint pos = spider->conn_link_idx[link_idx];
   DBUG_ENTER("spider_oracle_handler::show_records");
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -10965,6 +10854,8 @@ int spider_oracle_handler::show_records(
       /* retry */
       if ((error_num = spider_db_ping(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10974,6 +10865,8 @@ int spider_oracle_handler::show_records(
       }
       if ((error_num = spider_db_set_names(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -10990,12 +10883,16 @@ int spider_oracle_handler::show_records(
         -1,
         &spider->need_mons[link_idx])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_PRINT("info", ("spider error_num=%d 3", error_num));
         DBUG_RETURN(spider_db_errorno(conn));
       }
     } else {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11012,18 +10909,29 @@ int spider_oracle_handler::show_records(
   request_key.next = NULL;
   if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
-    if (error_num || (error_num = spider_db_errorno(conn)))
+    if (error_num)
     {
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       DBUG_PRINT("info", ("spider error_num=%d 5", error_num));
       DBUG_RETURN(error_num);
+    }
+    else if (error_num || (error_num = spider_db_errorno(conn)))
+    {
+      DBUG_PRINT("info", ("spider error_num=%d 6", error_num));
+      DBUG_RETURN(error_num);
     } else {
-      DBUG_PRINT("info", ("spider error_num=%d 6",
+      DBUG_PRINT("info", ("spider error_num=%d 7",
         ER_QUERY_ON_FOREIGN_DATA_SOURCE));
       DBUG_RETURN(ER_QUERY_ON_FOREIGN_DATA_SOURCE);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11056,9 +10964,12 @@ int spider_oracle_handler::show_autoinc(
   if (!oracle_share->show_autoinc)
     DBUG_RETURN(0);
 
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -11082,6 +10993,8 @@ int spider_oracle_handler::show_autoinc(
       /* retry */
       if ((error_num = spider_db_ping(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11091,6 +11004,8 @@ int spider_oracle_handler::show_autoinc(
       }
       if ((error_num = spider_db_set_names(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11107,12 +11022,16 @@ int spider_oracle_handler::show_autoinc(
         -1,
         &spider->need_mons[link_idx])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_PRINT("info", ("spider error_num=%d 3", error_num));
         DBUG_RETURN(spider_db_errorno(conn));
       }
     } else {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11129,18 +11048,29 @@ int spider_oracle_handler::show_autoinc(
   request_key.next = NULL;
   if (!(res = conn->db_conn->store_result(NULL, &request_key, &error_num)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
-    if (error_num || (error_num = spider_db_errorno(conn)))
+    if (error_num)
     {
+      SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+      pthread_mutex_unlock(&conn->mta_conn_mutex);
       DBUG_PRINT("info", ("spider error_num=%d 5", error_num));
       DBUG_RETURN(error_num);
+    }
+    else if ((error_num = spider_db_errorno(conn)))
+    {
+      DBUG_PRINT("info", ("spider error_num=%d 6", error_num));
+      DBUG_RETURN(error_num);
     } else {
-      DBUG_PRINT("info", ("spider error_num=%d 6",
+      DBUG_PRINT("info", ("spider error_num=%d 7",
         ER_QUERY_ON_FOREIGN_DATA_SOURCE));
       DBUG_RETURN(ER_QUERY_ON_FOREIGN_DATA_SOURCE);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11250,9 +11180,12 @@ ha_rows spider_oracle_handler::explain_select(
     DBUG_RETURN(HA_POS_ERROR);
   }
 
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
@@ -11278,6 +11211,8 @@ ha_rows spider_oracle_handler::explain_select(
       {
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11288,6 +11223,8 @@ ha_rows spider_oracle_handler::explain_select(
       {
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11306,6 +11243,8 @@ ha_rows spider_oracle_handler::explain_select(
         error_num = spider_db_errorno(conn);
         if (spider->check_error_mode(error_num))
           my_errno = error_num;
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11315,6 +11254,8 @@ ha_rows spider_oracle_handler::explain_select(
     } else {
       if (spider->check_error_mode(error_num))
         my_errno = error_num;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11334,6 +11275,8 @@ ha_rows spider_oracle_handler::explain_select(
     {
       if (spider->check_error_mode(error_num))
         my_errno = error_num;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11341,6 +11284,8 @@ ha_rows spider_oracle_handler::explain_select(
       DBUG_RETURN(HA_POS_ERROR);
     } else {
       my_errno = ER_QUERY_ON_FOREIGN_DATA_SOURCE;
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11348,6 +11293,8 @@ ha_rows spider_oracle_handler::explain_select(
       DBUG_RETURN(HA_POS_ERROR);
     }
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11381,13 +11328,18 @@ int spider_oracle_handler::lock_tables(
     }
     if (str->length())
     {
+      pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
       pthread_mutex_lock(&conn->mta_conn_mutex);
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
       conn->need_mon = &spider->need_mons[link_idx];
+      DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = TRUE;
       conn->mta_conn_mutex_unlock_later = TRUE;
       if ((error_num = spider_db_set_names(spider, conn, link_idx)))
       {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11403,10 +11355,14 @@ int spider_oracle_handler::lock_tables(
         -1,
         &spider->need_mons[link_idx])
       ) {
+        DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+        DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
         conn->mta_conn_mutex_lock_already = FALSE;
         conn->mta_conn_mutex_unlock_later = FALSE;
         DBUG_RETURN(spider_db_errorno(conn));
       }
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11452,13 +11408,18 @@ int spider_oracle_handler::disable_keys(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11474,11 +11435,15 @@ int spider_oracle_handler::disable_keys(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11501,13 +11466,18 @@ int spider_oracle_handler::enable_keys(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11523,11 +11493,15 @@ int spider_oracle_handler::enable_keys(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11551,13 +11525,18 @@ int spider_oracle_handler::check_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11573,11 +11552,15 @@ int spider_oracle_handler::check_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11601,13 +11584,18 @@ int spider_oracle_handler::repair_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11623,11 +11611,15 @@ int spider_oracle_handler::repair_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11650,13 +11642,18 @@ int spider_oracle_handler::analyze_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11672,11 +11669,15 @@ int spider_oracle_handler::analyze_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11699,13 +11700,18 @@ int spider_oracle_handler::optimize_table(
   {
     DBUG_RETURN(error_num);
   }
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
   pthread_mutex_lock(&conn->mta_conn_mutex);
   SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
   conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = TRUE;
   conn->mta_conn_mutex_unlock_later = TRUE;
   if ((error_num = spider_db_set_names(spider, conn, link_idx)))
   {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11721,11 +11727,15 @@ int spider_oracle_handler::optimize_table(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
   conn->mta_conn_mutex_lock_already = FALSE;
   conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -11751,6 +11761,14 @@ int spider_oracle_handler::flush_tables(
   }
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
     share);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     str->ptr(),
@@ -11758,9 +11776,17 @@ int spider_oracle_handler::flush_tables(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
@@ -11776,6 +11802,14 @@ int spider_oracle_handler::flush_logs(
   DBUG_PRINT("info",("spider this=%p", this));
   spider_conn_set_timeout_from_share(conn, link_idx, spider->trx->thd,
     share);
+  pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
+  pthread_mutex_lock(&conn->mta_conn_mutex);
+  SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
+  conn->need_mon = &spider->need_mons[link_idx];
+  DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = TRUE;
+  conn->mta_conn_mutex_unlock_later = TRUE;
   if (spider_db_query(
     conn,
     SPIDER_SQL_FLUSH_LOGS_STR,
@@ -11783,9 +11817,17 @@ int spider_oracle_handler::flush_logs(
     -1,
     &spider->need_mons[link_idx])
   ) {
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+    conn->mta_conn_mutex_lock_already = FALSE;
+    conn->mta_conn_mutex_unlock_later = FALSE;
     error_num = spider_db_errorno(conn);
     DBUG_RETURN(error_num);
   }
+  DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+  DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
+  conn->mta_conn_mutex_lock_already = FALSE;
+  conn->mta_conn_mutex_unlock_later = FALSE;
   SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
   pthread_mutex_unlock(&conn->mta_conn_mutex);
   DBUG_RETURN(0);
diff --git a/storage/spider/spd_include.h b/storage/spider/spd_include.h
index a6ce2efe774..a871e186d96 100644
--- a/storage/spider/spd_include.h
+++ b/storage/spider/spd_include.h
@@ -17,6 +17,8 @@
 #define SPIDER_HEX_VERSION 0x0302
 
 #if MYSQL_VERSION_ID < 50500
+#define pthread_mutex_assert_owner(A)
+#define pthread_mutex_assert_not_owner(A)
 #else
 #define my_free(A,B) my_free(A)
 #ifdef pthread_mutex_t
@@ -39,6 +41,8 @@
 #undef pthread_mutex_destroy
 #endif
 #define pthread_mutex_destroy mysql_mutex_destroy
+#define pthread_mutex_assert_owner(A) mysql_mutex_assert_owner(A)
+#define pthread_mutex_assert_not_owner(A) mysql_mutex_assert_not_owner(A)
 #ifdef pthread_cond_t
 #undef pthread_cond_t
 #endif
diff --git a/storage/spider/spd_table.cc b/storage/spider/spd_table.cc
index 7c591cf691d..39f51fa1b59 100644
--- a/storage/spider/spd_table.cc
+++ b/storage/spider/spd_table.cc
@@ -5815,13 +5815,18 @@ int spider_open_all_tables(
     }
     conn->error_mode &= spider_param_error_read_mode(thd, 0);
     conn->error_mode &= spider_param_error_write_mode(thd, 0);
+    pthread_mutex_assert_not_owner(&conn->mta_conn_mutex);
     pthread_mutex_lock(&conn->mta_conn_mutex);
     SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
     conn->need_mon = &mon_val;
+    DBUG_ASSERT(!conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(!conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = TRUE;
     conn->mta_conn_mutex_unlock_later = TRUE;
     if ((error_num = spider_db_before_query(conn, &mon_val)))
     {
+      DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+      DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
       conn->mta_conn_mutex_lock_already = FALSE;
       conn->mta_conn_mutex_unlock_later = FALSE;
       SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -5834,6 +5839,8 @@ int spider_open_all_tables(
       free_root(&mem_root, MYF(0));
       DBUG_RETURN(error_num);
     }
+    DBUG_ASSERT(conn->mta_conn_mutex_lock_already);
+    DBUG_ASSERT(conn->mta_conn_mutex_unlock_later);
     conn->mta_conn_mutex_lock_already = FALSE;
     conn->mta_conn_mutex_unlock_later = FALSE;
     SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);