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Adjust CreateCheckpoint so that buffer dumping activities and cleanup of

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dead xlog segments are not considered part of a critical section.  It is
not necessary to force a database-wide panic if we get a failure in these
operations.  Per recent trouble reports.
This commit is contained in:
Tom Lane 2003-05-10 18:01:31 +00:00
parent 199f24e19d
commit 8d86a96068
1 changed files with 31 additions and 4 deletions
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35
src/backend/access/transam/xlog.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.114 2003/04/25 19:45:08 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.115 2003/05/10 18:01:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2973,11 +2973,13 @@ CreateCheckPoint(bool shutdown, bool force)
elog(ERROR, "CreateCheckPoint: cannot be called inside transaction block");
/*
* Acquire CheckpointLock to ensure only one checkpoint happens at a time.
*
* The CheckpointLock can be held for quite a while, which is not good
* because we won't respond to a cancel/die request while waiting for
* an LWLock. (But the alternative of using a regular lock won't work
* for background checkpoint processes, which are not regular
* backends.) So, rather than use a plain LWLockAcquire, use this
* backends.) So, rather than use a plain LWLockAcquire, use this
* kluge to allow an interrupt to be accepted while we are waiting:
*/
while (!LWLockConditionalAcquire(CheckpointLock, LW_EXCLUSIVE))
@ -2986,6 +2988,9 @@ CreateCheckPoint(bool shutdown, bool force)
sleep(1);
}
/*
* Use a critical section to force system panic if we have trouble.
*/
START_CRIT_SECTION();
if (shutdown)
@ -3056,6 +3061,13 @@ CreateCheckPoint(bool shutdown, bool force)
/*
* Here we update the shared RedoRecPtr for future XLogInsert calls;
* this must be done while holding the insert lock AND the info_lck.
*
* Note: if we fail to complete the checkpoint, RedoRecPtr will be
* left pointing past where it really needs to point. This is okay;
* the only consequence is that XLogInsert might back up whole buffers
* that it didn't really need to. We can't postpone advancing RedoRecPtr
* because XLogInserts that happen while we are dumping buffers must
* assume that their buffer changes are not included in the checkpoint.
*/
{
/* use volatile pointer to prevent code rearrangement */
@ -3094,6 +3106,9 @@ CreateCheckPoint(bool shutdown, bool force)
*/
LWLockRelease(WALInsertLock);
/*
* Get the other info we need for the checkpoint record.
*/
LWLockAcquire(XidGenLock, LW_SHARED);
checkPoint.nextXid = ShmemVariableCache->nextXid;
LWLockRelease(XidGenLock);
@ -3107,10 +3122,18 @@ CreateCheckPoint(bool shutdown, bool force)
/*
* Having constructed the checkpoint record, ensure all shmem disk
* buffers and commit-log buffers are flushed to disk.
*
* This I/O could fail for various reasons. If so, we will fail to
* complete the checkpoint, but there is no reason to force a system
* panic. Accordingly, exit critical section while doing it.
*/
END_CRIT_SECTION();
CheckPointCLOG();
FlushBufferPool();
START_CRIT_SECTION();
/*
* Now insert the checkpoint record into XLOG.
*/
@ -3166,6 +3189,12 @@ CreateCheckPoint(bool shutdown, bool force)
UpdateControlFile();
LWLockRelease(ControlFileLock);
/*
* We are now done with critical updates; no need for system panic if
* we have trouble while fooling with offline log segments.
*/
END_CRIT_SECTION();
/*
* Delete offline log files (those no longer needed even for previous
* checkpoint).
@ -3185,8 +3214,6 @@ CreateCheckPoint(bool shutdown, bool force)
PreallocXlogFiles(recptr);
LWLockRelease(CheckpointLock);
END_CRIT_SECTION();
}
/*