From abc98dcc152bd3d8e2661c0f50988638725e838d Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 12 Sep 2004 18:30:50 +0000
Subject: [PATCH] When LockAcquire fails at the stage of creating a proclock
object, be sure to clean up the already-created lock object, if it has no
other references. Avoids possibly-permanent leak of shared memory.
---
src/backend/storage/lmgr/lock.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 55fba035a91..f90a3fd0e84 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.139 2004/08/29 05:06:48 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.140 2004/09/12 18:30:50 tgl Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@@ -602,7 +602,23 @@ LockAcquire(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
HASH_ENTER, &found);
if (!proclock)
{
+ /* Ooops, not enough shmem for the proclock */
+ if (lock->nRequested == 0)
+ {
+ /*
+ * There are no other requestors of this lock, so garbage-collect
+ * the lock object. We *must* do this to avoid a permanent leak
+ * of shared memory, because there won't be anything to cause
+ * anyone to release the lock object later.
+ */
+ Assert(SHMQueueEmpty(&(lock->procLocks)));
+ lock = (LOCK *) hash_search(LockMethodLockHash[lockmethodid],
+ (void *) &(lock->tag),
+ HASH_REMOVE, NULL);
+ }
LWLockRelease(masterLock);
+ if (!lock) /* hash remove failed? */
+ elog(WARNING, "lock table corrupted");
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory"),
@@ -1528,7 +1544,7 @@ LockReleaseAll(LOCKMETHODID lockmethodid, bool allxids)
if (!lock)
{
LWLockRelease(masterLock);
- elog(WARNING, "cannot remove lock from HTAB");
+ elog(WARNING, "lock table corrupted");
return FALSE;
}
}
--
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