From: Tom Lane <tgl@sss.pgh.pa.us>
To: Josh Berkus <josh@agliodbs.com>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Anyone seen this kind of lock pileup?
Date: Wed, 17 Nov 2010 16:58:52 -0500
Message-ID: <24934.1290031132@sss.pgh.pa.us> (raw)
In-Reply-To: <4CE412F4.4090101@agliodbs.com>
References: <4CE412F4.4090101@agliodbs.com>
Josh Berkus <josh@agliodbs.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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, josh@agliodbs.com
Subject: Re: Anyone seen this kind of lock pileup?
In-Reply-To: <24934.1290031132@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox