From: | Josh Berkus <josh(at)agliodbs(dot)com> |
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To: | postgres performance list <pgsql-performance(at)postgresql(dot)org> |
Subject: | Anyone seen this kind of lock pileup? |
Date: | 2010-11-17 17:37:56 |
Message-ID: | 4CE412F4.4090101@agliodbs.com |
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Lists: | pgsql-performance |
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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