mirror of
https://github.com/MariaDB/server.git
synced 2025-01-16 20:12:31 +01:00
97883d3c04
MEMORY LEAK. Background: - There are caches for stored functions and stored procedures (SP-cache); - There is no similar cache for events; - Triggers are cached together with TABLE objects; - Those SP-caches are per-session (i.e. specific to each session); - A stored routine is represented by a sp_head-instance internally; - SP-cache basically contains sp_head-objects of stored routines, which have been executed in a session; - sp_head-object is added into the SP-cache before the corresponding stored routine is executed; - SP-cache is flushed in the end of the session. The problem was that SP-cache might grow without any limit. Although this was not a pure memory leak (the SP-cache is flushed when session is closed), this is still a problem, because the user might take much memory by executing many stored routines. The patch fixes this problem in the least-intrusive way. A soft limit (similar to the size of table definition cache) is introduced. To represent such limit the new runtime configuration parameter 'stored_program_cache' is introduced. The value of this parameter is stored in the new global variable stored_program_cache_size that used to control the size of SP-cache to overflow. The parameter 'stored_program_cache' limits number of cached routines for each thread. It has the following min/default/max values given from support: min = 256, default = 256, max = 512 * 1024. Also it should be noted that this parameter limits the size of each cache (for stored procedures and for stored functions) separately. The SP-cache size is checked after top-level statement is parsed. If SP-cache size exceeds the limit specified by parameter 'stored_program_cache' then SP-cache is flushed and memory allocated for cache objects is freed. Such approach allows to flush cache safely when there are dependencies among stored routines. sql/mysqld.cc: Added global variable stored_program_cache_size to store value of configuration parameter 'stored-program-cache'. sql/mysqld.h: Added declaration of global variable stored_program_cache_size. sql/sp_cache.cc: Extended interface for sp_cache by adding helper routine sp_cache_enforce_limit to control size of stored routines cache for overflow. Also added method enforce_limit into class sp_cache that implements control of cache size for overflow. sql/sp_cache.h: Extended interface for sp_cache by adding standalone routine sp_cache_enforce_limit to control size of stored routines cache for overflow. sql/sql_parse.cc: Added flush of sp_cache after processing of next sql-statement received from a client. sql/sql_prepare.cc: Added flush of sp_cache after preparation/execution of next prepared sql-statement received from a client. sql/sys_vars.cc: Added support for configuration parameter stored-program-cache.
67 lines
2 KiB
C++
67 lines
2 KiB
C++
/* -*- C++ -*- */
|
|
/* Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; version 2 of the License.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
|
|
|
|
#ifndef _SP_CACHE_H_
|
|
#define _SP_CACHE_H_
|
|
|
|
#ifdef USE_PRAGMA_INTERFACE
|
|
#pragma interface /* gcc class implementation */
|
|
#endif
|
|
|
|
#include "my_global.h" /* ulong */
|
|
|
|
/*
|
|
Stored procedures/functions cache. This is used as follows:
|
|
* Each thread has its own cache.
|
|
* Each sp_head object is put into its thread cache before it is used, and
|
|
then remains in the cache until deleted.
|
|
*/
|
|
|
|
class sp_head;
|
|
class sp_cache;
|
|
class sp_name;
|
|
|
|
/*
|
|
Cache usage scenarios:
|
|
1. Application-wide init:
|
|
sp_cache_init();
|
|
|
|
2. SP execution in thread:
|
|
2.1 While holding sp_head* pointers:
|
|
|
|
// look up a routine in the cache (no checks if it is up to date or not)
|
|
sp_cache_lookup();
|
|
|
|
sp_cache_insert();
|
|
sp_cache_invalidate();
|
|
|
|
2.2 When not holding any sp_head* pointers:
|
|
sp_cache_flush_obsolete();
|
|
|
|
3. Before thread exit:
|
|
sp_cache_clear();
|
|
*/
|
|
|
|
void sp_cache_init();
|
|
void sp_cache_clear(sp_cache **cp);
|
|
void sp_cache_insert(sp_cache **cp, sp_head *sp);
|
|
sp_head *sp_cache_lookup(sp_cache **cp, sp_name *name);
|
|
void sp_cache_invalidate();
|
|
void sp_cache_flush_obsolete(sp_cache **cp, sp_head **sp);
|
|
ulong sp_cache_version();
|
|
void sp_cache_enforce_limit(sp_cache *cp, ulong upper_limit_for_elements);
|
|
|
|
#endif /* _SP_CACHE_H_ */
|