From: Josh Berkus <josh@agliodbs.com>
To: postgres performance list <pgsql-performance@postgresql.org>
Subject: Anyone seen this kind of lock pileup?
Date: Wed, 17 Nov 2010 09:37:56 -0800
Message-ID: <4CE412F4.4090101@agliodbs.com> (raw)
All,
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.
Has anyone else seen something like this? Any idea what causes it?
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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To: pgsql-performance@postgresql.org
Cc: josh@agliodbs.com
Subject: Re: Anyone seen this kind of lock pileup?
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