From: Ivan Voras <ivoras@freebsd.org>
To: pgsql-performance@postgresql.org
Subject: Re: Anyone seen this kind of lock pileup?
Date: Wed, 17 Nov 2010 23:53:58 +0100
Message-ID: <ic1me7$cio$1@dough.gmane.org> (raw)
In-Reply-To: <4CE412F4.4090101@agliodbs.com>
References: <4CE412F4.4090101@agliodbs.com>
On 11/17/10 18:37, Josh Berkus wrote:
> All,
>
> Having an interesting issue on one 8.4 database. Due to poor application
> design, the application is requesting 8-15 exclusive (update) locks on
> the same row on parallel connections pretty much simultaneously (i.e. <
> 50ms apart).
>
> What's odd about this is that the resulting "lock pileup" takes a
> mysterious 2-3.5 seconds to clear, despite the fact that none of the
> connections are *doing* anything during that time, nor are there
> deadlock errors. In theory at least, the locks should clear out in
> reverse order in less than a second; none of the individual statements
> takes more than 10ms to execute.
Just a random guess: a timeout-supported livelock? (of course if there
is any timeout-and-retry protocol going on and the timeout intervals are
non-randomized).
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To: pgsql-performance@postgresql.org
Cc: ivoras@freebsd.org
Subject: Re: Anyone seen this kind of lock pileup?
In-Reply-To: <ic1me7$cio$1@dough.gmane.org>
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