MDEV-15149 Assert upon concurrent creating / querying sequences

Problem was that sequence_insert closed and reopened the like table
without proper locking.  Fixed by ensuring that the like table is
not reopened in sequence_insert

1 files changed, 2 insertions, 0 deletions

diff --git a/sql/table_cache.cc b/sql/table_cache.cc
index 18ea7f83964..e524e0995e2 100644
--- a/sql/table_cache.cc
+++ b/sql/table_cache.cc
@@ -460,6 +460,7 @@ static TABLE *tc_acquire_table(THD *thd, TDC_element *element)
 void tc_release_table(TABLE *table)
 {
   uint32 i= table->instance;
+  DBUG_ENTER("tc_release_table");
   DBUG_ASSERT(table->in_use);
   DBUG_ASSERT(table->file);
 
@@ -478,6 +479,7 @@ void tc_release_table(TABLE *table)
     tc[i].free_tables.push_back(table);
     mysql_mutex_unlock(&tc[i].LOCK_table_cache);
   }
+  DBUG_VOID_RETURN;
 }