Bug #87277 count handler opened by innodb

• Submitted: 2 Aug 2017 6:41
• Reporter: yx jiang
• Status: Open
• Category: MySQL Server
• Severity: S4 (Feature request)
• Version: 5.7.18
• OS: CentOS (6.4)
• CPU Architecture: Any
• Tags: innodb memory monitor

[2 Aug 2017 6:41] yx jiang

Description:
If too many connections open too many tables, MySQL looks like having memory leak.But using valgrind does not detect any leak.

This happens when we create more than ten thousand tables in develop environment.

So we try to add monitor to hanlder opening count to tell our maintainer, this is the most likely root cause.

How to repeat:
N/A

Suggested fix:
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha
index 243f405..a9b304e 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -118,6 +118,9 @@ enum_tx_isolation thd_get_trx_isolation(const THD* thd);
 /* for ha_innopart, Native InnoDB Partitioning. */
 #include "ha_innopart.h"

+ulonglong innodb_handler_open = 0;
+ulong innodb_handler_size = sizeof(ha_innobase);
+
 /** to protect innobase_open_files */
 static mysql_mutex_t innobase_share_mutex;
 /** to force correct commit order in binlog */
@@ -2805,7 +2808,10 @@ ha_innobase::ha_innobase(
        m_start_of_scan(),
        m_num_write_row(),
         m_mysql_has_locked()
-{}
+{
+  __sync_fetch_and_add(&innodb_handler_open, 1);
+
+}

 /*********************************************************************//**
 Destruct ha_innobase handler. */
@@ -2813,6 +2819,7 @@ Destruct ha_innobase handler. */
 ha_innobase::~ha_innobase()
 /*======================*/
 {
+  __sync_fetch_and_sub(&innodb_handler_open, 1);
 }

 /*********************************************************************//**
@@ -20146,6 +20153,16 @@ static MYSQL_SYSVAR_BOOL(sync_debug, srv_sync_debug,
   NULL, NULL, FALSE);
 #endif /* UNIV_DEBUG */

+static MYSQL_SYSVAR_ULONGLONG(handler_open, innodb_handler_open,
+  PLUGIN_VAR_READONLY,
+  "hanlder openned by innobase",
+  NULL, NULL, 0, 0, ULLONG_MAX, 0);
+
+static MYSQL_SYSVAR_ULONG(handler_size, innodb_handler_size,
+  PLUGIN_VAR_READONLY,
+  "hanlder size of innobase",
+  NULL, NULL, sizeof(ha_innobase), 0, ULONG_MAX, 0);
+
 static struct st_mysql_sys_var* innobase_system_variables[]= {
   MYSQL_SYSVAR(api_trx_level),
   MYSQL_SYSVAR(api_bk_commit_interval),
@@ -20318,6 +20335,8 @@ static struct st_mysql_sys_var* innobase_system_variable
   MYSQL_SYSVAR(master_thread_disabled_debug),
   MYSQL_SYSVAR(sync_debug),
 #endif /* UNIV_DEBUG */
+  MYSQL_SYSVAR(handler_open),
+  MYSQL_SYSVAR(handler_size),
   NULL
 };