From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Dunstan <andrew.dunstan@pgexperts.com>
Cc: pgsql-perform <pgsql-performance@postgresql.org>
Subject: Re: backend suddenly becomes slow, then remains slow
Date: Fri, 14 Dec 2012 14:56:00 -0500
Message-ID: <5309.1355514960@sss.pgh.pa.us> (raw)
In-Reply-To: <50CB7284.3020008@pgexperts.com>
References: <50CB7284.3020008@pgexperts.com>
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Andrew Dunstan <andrew.dunstan@pgexperts.com> writes:
> One of my clients has an odd problem. Every so often a backend will
> suddenly become very slow. The odd thing is that once this has happened
> it remains slowed down, for all subsequent queries. Zone reclaim is off.
> There is no IO or CPU spike, no checkpoint issues or stats timeouts, no
> other symptom that we can see. The problem was a lot worse that it is
> now, but two steps have alleviated it mostly, but not completely: much
> less aggressive autovacuuming and reducing the maximum lifetime of
> backends in the connection pooler to 30 minutes.
> It's got us rather puzzled. Has anyone seen anything like this?
Maybe the kernel is auto-nice'ing the process once it's accumulated X
amount of CPU time?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, andrew.dunstan@pgexperts.com
Subject: Re: backend suddenly becomes slow, then remains slow
In-Reply-To: <5309.1355514960@sss.pgh.pa.us>
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