thr0loc.c, srv0start.c, srv0srv.c, srv0srv.h, os0thread.h, ha_innodb.cc:

  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB


sql/ha_innodb.cc:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB
innobase/include/os0thread.h:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB
innobase/include/srv0srv.h:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB
innobase/srv/srv0srv.c:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB
innobase/srv/srv0start.c:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB
innobase/thr/thr0loc.c:
  Backport from 4.1: reduce InnoDB memory consumption if buf pool < 8 MB

2 files changed, 33 insertions, 3 deletions

diff --git a/innobase/srv/srv0srv.c b/innobase/srv/srv0srv.c
index f31d275eff0..8aba1b4f414 100644
--- a/innobase/srv/srv0srv.c
+++ b/innobase/srv/srv0srv.c
@@ -142,7 +142,7 @@ byte	srv_latin1_ordering[256]	/* The sort order table of the latin1
 		
 ulint	srv_pool_size		= ULINT_MAX;	/* size in database pages;
 						MySQL originally sets this
-						value in megabytes */ 
+						value in bytes */ 
 ulint	srv_mem_pool_size	= ULINT_MAX;	/* size in bytes */ 
 ulint	srv_lock_table_size	= ULINT_MAX;
 
@@ -169,6 +169,12 @@ the user from forgetting the innodb_force_recovery keyword to my.cnf */
 
 ulint	srv_force_recovery	= 0;
 /*-----------------------*/
+/* We are prepared for a situation that we have this many threads waiting for
+a semaphore inside InnoDB. innobase_start_or_create_for_mysql() sets the
+value. */
+
+ulint   srv_max_n_threads       = 0;
+
 /* The following controls how many threads we let inside InnoDB concurrently:
 threads waiting for locks are not counted into the number because otherwise
 we could get a deadlock. MySQL creates a thread for each user session, and
@@ -208,7 +214,7 @@ struct srv_conc_slot_struct{
 
 UT_LIST_BASE_NODE_T(srv_conc_slot_t)	srv_conc_queue;	/* queue of threads
 							waiting to get in */
-srv_conc_slot_t	srv_conc_slots[OS_THREAD_MAX_N];	/* array of wait
+srv_conc_slot_t*			srv_conc_slots;	/* array of wait
 							slots */
 
 /* Number of times a thread is allowed to enter InnoDB within the same
@@ -1693,6 +1699,8 @@ srv_init(void)
 	os_fast_mutex_init(&srv_conc_mutex);
 	
 	UT_LIST_INIT(srv_conc_queue);
+
+	srv_conc_slots = mem_alloc(OS_THREAD_MAX_N * sizeof(srv_conc_slot_t));
 	
 	for (i = 0; i < OS_THREAD_MAX_N; i++) {
 		conc_slot = srv_conc_slots + i;
@@ -1740,7 +1748,7 @@ srv_conc_enter_innodb(
 			thread */
 {
 	ibool			has_slept = FALSE;
-	srv_conc_slot_t*	slot;
+	srv_conc_slot_t*	slot	  = NULL;
 	ulint			i;
 	char                    err_buf[1000];
 
diff --git a/innobase/srv/srv0start.c b/innobase/srv/srv0start.c
index a85c3615c1b..af4ca71d443 100644
--- a/innobase/srv/srv0start.c
+++ b/innobase/srv/srv0start.c
@@ -1087,6 +1087,28 @@ innobase_start_or_create_for_mysql(void)
 	  	return(DB_ERROR);
 	}
 
+        /* Set the maximum number of threads which can wait for a semaphore
+        inside InnoDB */
+#if defined(__WIN__) || defined(__NETWARE__)
+
+/* Create less event semaphores because Win 98/ME had difficulty creating
+40000 event semaphores.
+Comment from Novell, Inc.: also, these just take a lot of memory on
+NetWare. */
+        srv_max_n_threads = 1000;
+#else
+        if (srv_pool_size >= 8 * 1024 * 1024) {
+                                  /* Here we still have srv_pool_size counted
+                                  in bytes, srv_boot converts the value to
+                                  pages; if buffer pool is less than 8 MB,
+                                  assume fewer threads. */
+                srv_max_n_threads = 10000;
+        } else {
+		srv_max_n_threads = 1000;       /* saves several MB of memory,
+                                                especially in 64-bit
+                                                computers */
+        }
+#endif
 	err = srv_boot();
 
 	if (err != DB_SUCCESS) {