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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.
68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
/* -*- C++ -*- */
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/* Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef _SP_CACHE_H_
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#define _SP_CACHE_H_
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#ifdef USE_PRAGMA_INTERFACE
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#pragma interface /* gcc class implementation */
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#endif
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#include "my_global.h" /* ulong */
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/*
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Stored procedures/functions cache. This is used as follows:
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* Each thread has its own cache.
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* Each sp_head object is put into its thread cache before it is used, and
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then remains in the cache until deleted.
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*/
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class sp_head;
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class sp_cache;
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class sp_name;
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/*
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Cache usage scenarios:
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1. Application-wide init:
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sp_cache_init();
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2. SP execution in thread:
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2.1 While holding sp_head* pointers:
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// look up a routine in the cache (no checks if it is up to date or not)
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sp_cache_lookup();
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sp_cache_insert();
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sp_cache_invalidate();
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2.2 When not holding any sp_head* pointers:
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sp_cache_flush_obsolete();
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3. Before thread exit:
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sp_cache_clear();
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*/
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void sp_cache_init();
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void sp_cache_clear(sp_cache **cp);
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void sp_cache_insert(sp_cache **cp, sp_head *sp);
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sp_head *sp_cache_lookup(sp_cache **cp, sp_name *name);
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void sp_cache_invalidate();
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void sp_cache_flush_obsolete(sp_cache **cp, sp_head **sp);
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ulong sp_cache_version();
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void sp_cache_enforce_limit(sp_cache *cp, ulong upper_limit_for_elements);
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#endif /* _SP_CACHE_H_ */
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