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Replace CLOBBER_CACHE_ALWAYS with run-time GUC

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Forced cache invalidation (CLOBBER_CACHE_ALWAYS) has been impractical
to use for testing in PostgreSQL because it's so slow and because it's
toggled on/off only at build time.  It is helpful when hunting bugs in
any code that uses the sycache/relcache because causes cache
invalidations to be injected whenever it would be possible for an
invalidation to occur, whether or not one was really pending.

Address this by providing run-time control over cache clobber
behaviour using the new debug_invalidate_system_caches_always GUC.
Support is not compiled in at all unless assertions are enabled or
CLOBBER_CACHE_ENABLED is explicitly defined at compile time.  It
defaults to 0 if compiled in, so it has negligible effect on assert
build performance by default.

When support is compiled in, test code can now set
debug_invalidate_system_caches_always=1 locally to a backend to test
specific queries, functions, extensions, etc.  Or tests can toggle it
globally for a specific test case while retaining normal performance
during test setup and teardown.

For backwards compatibility with existing test harnesses and scripts,
debug_invalidate_system_caches_always defaults to 1 if
CLOBBER_CACHE_ALWAYS is defined, and to 3 if CLOBBER_CACHE_RECURSIVE
is defined.

CLOBBER_CACHE_ENABLED is now visible in pg_config_manual.h, as is the
related RECOVER_RELATION_BUILD_MEMORY setting for the relcache.

Author: Craig Ringer <craig.ringer@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/CAMsr+YF=+ctXBZj3ywmvKNUjWpxmuTuUKuv-rgbHGX5i5pLstQ@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2021-01-06 10:15:19 +01:00
parent 8900b5a9d5
commit 4656e3d668
9 changed files with 169 additions and 54 deletions
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39
src/include/pg_config_manual.h
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@@ -309,6 +309,45 @@
*/
/* #define RANDOMIZE_ALLOCATED_MEMORY */
/*
* For cache invalidation debugging, define CLOBBER_CACHE_ENABLED to enable
* use of the debug_invalidate_system_caches_always GUC to aggressively flush
* syscache/relcache entries whenever it's possible to deliver invalidations.
* See AcceptInvalidationMessages() in src/backend/utils/cache/inval.c for
* details.
*
* USE_ASSERT_CHECKING builds default to enabling this. It's possible to use
* CLOBBER_CACHE_ENABLED without a cassert build and the implied
* CLOBBER_FREED_MEMORY and MEMORY_CONTEXT_CHECKING options but it's unlikely
* to be as effective at identifying problems.
*/
/* #define CLOBBER_CACHE_ENABLED */
#if defined(USE_ASSERT_CHECKING) && !defined(CLOBBER_CACHE_ENABLED)
#define CLOBBER_CACHE_ENABLED
#endif
/*
* Backwards compatibility for the older compile-time-only cache clobber
* macros.
*/
#if !defined(CLOBBER_CACHE_ENABLED) && (defined(CLOBBER_CACHE_ALWAYS) || defined(CLOBBER_CACHE_RECURSIVELY))
#define CLOBBER_CACHE_ENABLED
#endif
/*
* Recover memory used for relcache entries when invalidated. See
* RelationBuildDescr() in src/backend/utils/cache/relcache.c.
*
* This is active automatically for clobber cache builds when clobbering is
* active, but can be overridden here by explicitly defining
* RECOVER_RELATION_BUILD_MEMORY. Define to 1 to always free relation cache
* memory even when clobber is off, or to 0 to never free relation cache
* memory even when clobbering is on.
*/
/* #define RECOVER_RELATION_BUILD_MEMORY 0 */ /* Force disable */
/* #define RECOVER_RELATION_BUILD_MEMORY 1 */ /* Force enable */
/*
* Define this to force all parse and plan trees to be passed through
* copyObject(), to facilitate catching errors and omissions in