*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.176 2007/02/01 19:10:28 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.177 2007/07/16 21:09:50 tgl Exp $
*
* NOTES
* A lock table is a shared memory hash table. When
el++;
}
- /* And release locks */
+ /*
+ * And release locks. We do this in reverse order for two reasons:
+ * (1) Anyone else who needs more than one of the locks will be trying
+ * to lock them in increasing order; we don't want to release the other
+ * process until it can get all the locks it needs.
+ * (2) This avoids O(N^2) behavior inside LWLockRelease.
+ */
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
LWLockRelease(FirstLockMgrLock + i);
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.190 2007/06/19 22:01:15 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.191 2007/07/16 21:09:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
}
/*
- * Release locks acquired at head of routine. Order is not critical, so
- * do it back-to-front to avoid waking another CheckDeadLock instance
- * before it can get all the locks.
+ * And release locks. We do this in reverse order for two reasons:
+ * (1) Anyone else who needs more than one of the locks will be trying
+ * to lock them in increasing order; we don't want to release the other
+ * process until it can get all the locks it needs.
+ * (2) This avoids O(N^2) behavior inside LWLockRelease.
*/
check_done:
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)