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Give the ResourceOwner mechanism full responsibility for releasing buffer

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pins at end of transaction, and reduce AtEOXact_Buffers to an Assert
cross-check that this was done correctly.  When not USE_ASSERT_CHECKING,
AtEOXact_Buffers is a complete no-op.  This gets rid of an O(NBuffers)
bottleneck during transaction commit/abort, which recent testing has shown
becomes significant above a few tens of thousands of shared buffers.
This commit is contained in:
Tom Lane
2004-10-16 18:57:26 +00:00
parent 1c2de47746
commit fdd13f1568
6 changed files with 95 additions and 72 deletions
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75
src/backend/storage/buffer/bufmgr.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.179 2004/10/16 18:05:06 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.180 2004/10/16 18:57:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -851,35 +851,45 @@ ResetBufferUsage(void)
/*
* AtEOXact_Buffers - clean up at end of transaction.
*
* During abort, we need to release any buffer pins we're holding
* (this cleans up in case ereport interrupted a routine that pins a
* buffer). During commit, we shouldn't need to do that, but check
* anyway to see if anyone leaked a buffer reference count.
* As of PostgreSQL 8.0, buffer pins should get released by the
* ResourceOwner mechanism. This routine is just a debugging
* cross-check that no pins remain.
*/
void
AtEOXact_Buffers(bool isCommit)
{
#ifdef USE_ASSERT_CHECKING
int i;
for (i = 0; i < NBuffers; i++)
{
Assert(PrivateRefCount[i] == 0);
}
AtEOXact_LocalBuffers(isCommit);
#endif
}
/*
* Ensure we have released all shared-buffer locks and pins during backend exit
*/
void
AtProcExit_Buffers(void)
{
int i;
AbortBufferIO();
UnlockBuffers();
for (i = 0; i < NBuffers; i++)
{
if (PrivateRefCount[i] != 0)
{
BufferDesc *buf = &(BufferDescriptors[i]);
if (isCommit)
elog(WARNING,
"buffer refcount leak: [%03d] "
"(rel=%u/%u/%u, blockNum=%u, flags=0x%x, refcount=%u %d)",
i,
buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
buf->tag.rnode.relNode,
buf->tag.blockNum, buf->flags,
buf->refcount, PrivateRefCount[i]);
/*
* We don't worry about updating the ResourceOwner structures;
* resowner.c will clear them for itself.
* We don't worry about updating ResourceOwner; if we even got
* here, it suggests that ResourceOwners are messed up.
*/
PrivateRefCount[i] = 1; /* make sure we release shared pin */
LWLockAcquire(BufMgrLock, LW_EXCLUSIVE);
@ -888,8 +898,37 @@ AtEOXact_Buffers(bool isCommit)
Assert(PrivateRefCount[i] == 0);
}
}
}
AtEOXact_LocalBuffers(isCommit);
/*
* Helper routine to issue warnings when a buffer is unexpectedly pinned
*/
void
PrintBufferLeakWarning(Buffer buffer)
{
BufferDesc *buf;
int32 loccount;
Assert(BufferIsValid(buffer));
if (BufferIsLocal(buffer))
{
buf = &LocalBufferDescriptors[-buffer - 1];
loccount = LocalRefCount[-buffer - 1];
}
else
{
buf = &BufferDescriptors[buffer - 1];
loccount = PrivateRefCount[buffer - 1];
}
elog(WARNING,
"buffer refcount leak: [%03d] "
"(rel=%u/%u/%u, blockNum=%u, flags=0x%x, refcount=%u %d)",
buffer,
buf->tag.rnode.spcNode, buf->tag.rnode.dbNode,
buf->tag.rnode.relNode,
buf->tag.blockNum, buf->flags,
buf->refcount, loccount);
}
/*