From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Josh Berkus <josh(at)agliodbs(dot)com> |
Cc: | postgres performance list <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Anyone seen this kind of lock pileup? |
Date: | 2010-11-17 21:58:52 |
Message-ID: | 24934.1290031132@sss.pgh.pa.us |
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Lists: | pgsql-performance |
Josh Berkus <josh(at)agliodbs(dot)com> writes:
> Having an interesting issue on one 8.4 database. Due to poor
> application design, the application is requesting 8-15 exclusive
> (update) locks on the same row on parallel connections pretty much
> simultaneously (i.e. < 50ms apart).
> What's odd about this is that the resulting "lock pileup" takes a
> mysterious 2-3.5 seconds to clear, despite the fact that none of the
> connections are *doing* anything during that time, nor are there
> deadlock errors. In theory at least, the locks should clear out in
> reverse order in less than a second; none of the individual statements
> takes more than 10ms to execute.
Hmm ... can you extract a test case? Or at least strace the backends
involved?
regards, tom lane
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