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From: Craig James <craig_james@emolecules.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Occasional giant spikes in CPU load
Date: Fri, 25 Jun 2010 06:48:43 -0700
Message-ID: <4C24B3BB.3070901@emolecules.com> (raw)
In-Reply-To: <23596.1277438692@sss.pgh.pa.us>
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	<23596.1277438692@sss.pgh.pa.us>

On 6/24/10 9:04 PM, Tom Lane wrote:
> Craig James<craig_james@emolecules.com>  writes:
>> So what is it that will cause every single Postgres backend to come to life at the same moment, when there's no real load on the server?  Maybe if a backend crashes?  Some other problem?
>
> sinval queue overflow comes to mind ... although that really shouldn't
> happen if there's "no real load" on the server.  What PG version is
> this?

8.3.10.  Upgraded based on your advice when I first asked this question.

>   Also, the pg_stat_activity view contents when this happens would
> probably be more useful to look at than "top" output.

I'll try.  It's hard to discover anything because the whole machine is overwhelmed when this happens.  The only way I got the top(1) output was by running it high priority as root using nice(1).  I can't do that with a Postgres backend, but I'll see what I can do.

Craig



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