| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Richard Huxton <dev(at)archonet(dot)com> |
| Cc: | Adrian Moisey <adrian(at)careerjunction(dot)co(dot)za>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: strange pauses |
| Date: | 2008-01-16 15:23:06 |
| Message-ID: | 23693.1200496986@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Richard Huxton <dev(at)archonet(dot)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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