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Add a small cache of locks owned by a resource owner in ResourceOwner.

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This speeds up reassigning locks to the parent owner, when the transaction
holds a lot of locks, but only a few of them belong to the current resource
owner. This is particularly helps pg_dump when dumping a large number of
objects.

The cache can hold up to 15 locks in each resource owner. After that, the
cache is marked as overflowed, and we fall back to the old method of
scanning the whole local lock table. The tradeoff here is that the cache has
to be scanned whenever a lock is released, so if the cache is too large,
lock release becomes more expensive. 15 seems enough to cover pg_dump, and
doesn't have much impact on lock release.

Jeff Janes, reviewed by Amit Kapila and Heikki Linnakangas.
This commit is contained in:
Heikki Linnakangas
2012-06-21 15:01:17 +03:00
parent dfd9c116cc
commit eeb6f37d89
4 changed files with 210 additions and 58 deletions
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4
src/include/storage/lock.h
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@@ -492,8 +492,8 @@ extern bool LockRelease(const LOCKTAG *locktag,
LOCKMODE lockmode, bool sessionLock);
extern void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks);
extern void LockReleaseSession(LOCKMETHODID lockmethodid);
extern void LockReleaseCurrentOwner(void);
extern void LockReassignCurrentOwner(void);
extern void LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks);
extern void LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks);
extern VirtualTransactionId *GetLockConflicts(const LOCKTAG *locktag,
LOCKMODE lockmode);
extern void AtPrepare_Locks(void);

5
src/include/utils/resowner.h
View File

@@ -20,6 +20,7 @@
#define RESOWNER_H
#include "storage/fd.h"
#include "storage/lock.h"
#include "utils/catcache.h"
#include "utils/plancache.h"
#include "utils/snapshot.h"
@@ -89,6 +90,10 @@ extern void ResourceOwnerEnlargeBuffers(ResourceOwner owner);
extern void ResourceOwnerRememberBuffer(ResourceOwner owner, Buffer buffer);
extern void ResourceOwnerForgetBuffer(ResourceOwner owner, Buffer buffer);
/* support for local lock management */
extern void ResourceOwnerRememberLock(ResourceOwner owner, LOCALLOCK *locallock);
extern void ResourceOwnerForgetLock(ResourceOwner owner, LOCALLOCK *locallock);
/* support for catcache refcount management */
extern void ResourceOwnerEnlargeCatCacheRefs(ResourceOwner owner);
extern void ResourceOwnerRememberCatCacheRef(ResourceOwner owner,