MDEV-6933: Spurious lock_wait_timeout_thread wakeup in lock_wait_suspend_thread()

Merged Facebooks commit 6e06bbfa315ffb97d713dd6e672d6054036ddc21
authored by Inaam Rana from https://github.com/facebook/mysql-5.6.

Fixes MySQL bug http://bugs.mysql.com/bug.php?id=72123

lock_timeout thread works in a tight loop waking up every second
and checking for lock_wait_timeout. In addition, when a mysql
thread is forced to wait on a lock, it signals the lock_timeout thread
as well. This call is not required. In a heavily contended workload
each thread going to wait will signal the lock_timeout thread making
it work all the time. As lock_timeout thread scans the array of
waiting threads under lock_sys::wait_mutex which is already very
hot in contneded loads, these extra scans can cause significanct
performance regression.

Also, in various codepaths lock_timeout thread is signalled where
actual intention was to signal the innodb monitor thread.

storage/innobase/buf/buf0lru.cc

@@ -1193,7 +1193,7 @@ buf_LRU_check_size_of_non_data_objects(
 
 			buf_lru_switched_on_innodb_mon = TRUE;
 			srv_print_innodb_monitor = TRUE;
-			os_event_set(lock_sys->timeout_event);
+			os_event_set(srv_monitor_event);
 		}
 	} else if (buf_lru_switched_on_innodb_mon) {
 
@@ -1342,7 +1342,7 @@ buf_LRU_get_free_block(
 		mon_value_was = srv_print_innodb_monitor;
 		started_monitor = TRUE;
 		srv_print_innodb_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	}
 
 	/* If we have scanned the whole LRU and still are unable to

storage/innobase/handler/ha_innodb.cc

@@ -16019,9 +16019,8 @@ innodb_status_output_update(
 	const void*			save __attribute__((unused)))
 {
 	*static_cast<my_bool*>(var_ptr) = *static_cast<const my_bool*>(save);
-	/* The lock timeout monitor thread also takes care of this
-	output. */
-	os_event_set(lock_sys->timeout_event);
+	/* Wakeup server monitor thread. */
+	os_event_set(srv_monitor_event);
 }
 
 static SHOW_VAR innodb_status_variables_export[]= {

storage/innobase/lock/lock0wait.cc

@@ -259,10 +259,6 @@ lock_wait_suspend_thread(
 		}
 	}
 
-	/* Wake the lock timeout monitor thread, if it is suspended */
-
-	os_event_set(lock_sys->timeout_event);
-
 	lock_wait_mutex_exit();
 	trx_mutex_exit(trx);
 

storage/innobase/row/row0mysql.cc

@@ -2200,23 +2200,23 @@ row_create_table_for_mysql(
 		/* The lock timeout monitor thread also takes care
 		of InnoDB monitor prints */
 
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_lock_monitor)) {
 
 		srv_print_innodb_monitor = TRUE;
 		srv_print_innodb_lock_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_tablespace_monitor)) {
 
 		srv_print_innodb_tablespace_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_table_monitor)) {
 
 		srv_print_innodb_table_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 #ifdef UNIV_MEM_DEBUG
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_mem_validate)) {

storage/innobase/sync/sync0arr.cc

@@ -1074,7 +1074,7 @@ sync_array_print_long_waits(
 			(ulong) os_file_n_pending_pwrites);
 
 		srv_print_innodb_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 
 		os_thread_sleep(30000000);
 

storage/xtradb/buf/buf0lru.cc

@@ -1282,7 +1282,7 @@ buf_LRU_check_size_of_non_data_objects(
 
 			buf_lru_switched_on_innodb_mon = TRUE;
 			srv_print_innodb_monitor = TRUE;
-			os_event_set(lock_sys->timeout_event);
+			os_event_set(srv_monitor_event);
 		}
 	} else if (buf_lru_switched_on_innodb_mon) {
 
@@ -1497,7 +1497,7 @@ buf_LRU_get_free_block(
 		mon_value_was = srv_print_innodb_monitor;
 		started_monitor = TRUE;
 		srv_print_innodb_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	}
 
 	/* If we have scanned the whole LRU and still are unable to

storage/xtradb/handler/ha_innodb.cc

@@ -17055,9 +17055,8 @@ innodb_status_output_update(
 	const void*			save __attribute__((unused)))
 {
 	*static_cast<my_bool*>(var_ptr) = *static_cast<const my_bool*>(save);
-	/* The lock timeout monitor thread also takes care of this
-	output. */
-	os_event_set(lock_sys->timeout_event);
+	/* Wakeup server monitor thread. */
+	os_event_set(srv_monitor_event);
 }
 
 static SHOW_VAR innodb_status_variables_export[]= {

storage/xtradb/lock/lock0wait.cc

@@ -259,10 +259,6 @@ lock_wait_suspend_thread(
 		}
 	}
 
-	/* Wake the lock timeout monitor thread, if it is suspended */
-
-	os_event_set(lock_sys->timeout_event);
-
 	lock_wait_mutex_exit();
 	trx_mutex_exit(trx);
 

storage/xtradb/row/row0mysql.cc

@@ -2214,23 +2214,23 @@ row_create_table_for_mysql(
 		/* The lock timeout monitor thread also takes care
 		of InnoDB monitor prints */
 
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_lock_monitor)) {
 
 		srv_print_innodb_monitor = TRUE;
 		srv_print_innodb_lock_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_tablespace_monitor)) {
 
 		srv_print_innodb_tablespace_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_table_monitor)) {
 
 		srv_print_innodb_table_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 #ifdef UNIV_MEM_DEBUG
 	} else if (STR_EQ(table_name, table_name_len,
 			  S_innodb_mem_validate)) {

storage/xtradb/sync/sync0arr.cc

@@ -1166,7 +1166,7 @@ sync_array_print_long_waits(
 			(ulong) os_file_n_pending_pwrites);
 
 		srv_print_innodb_monitor = TRUE;
-		os_event_set(lock_sys->timeout_event);
+		os_event_set(srv_monitor_event);
 
 		os_thread_sleep(30000000);