From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Huxton <dev@archonet.com>
Cc: Adrian Moisey <adrian@careerjunction.co.za>
Cc: pgsql-performance@postgresql.org
Subject: Re: strange pauses
Date: Wed, 16 Jan 2008 10:23:06 -0500
Message-ID: <23693.1200496986@sss.pgh.pa.us> (raw)
In-Reply-To: <478DE16F.50308@archonet.com>
References: <478DDF83.8070106@careerjunction.co.za>
<478DE16F.50308@archonet.com>
Richard Huxton <dev@archonet.com> writes:
> Adrian Moisey wrote:
>> If I tail the logs, I see a steady stream of functions that took longer
>> then 5 seconds. But every now and then I see nothing for 3 minutes and
>> after that a whole bunch (about 20 - 30) queries all finishing at the
>> same second.
> Search this list for references to "checkpoints". If you run
> vmstat/iostat for a bit you should see bursts of disk activity at those
> times.
A different line of thought is that something is taking out an exclusive
lock on a table that all these queries need. If vmstat doesn't show any
burst of activity during these pauses, look into pg_locks.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, dev@archonet.com, adrian@careerjunction.co.za
Subject: Re: strange pauses
In-Reply-To: <23693.1200496986@sss.pgh.pa.us>
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