Received: from maia.hub.org (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id B7097632EFE for ; Wed, 7 Apr 2010 18:40:29 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 35569-10 for ; Wed, 7 Apr 2010 21:40:18 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from spinlock.commandprompt.com (host-215.commandprompt.net [207.173.203.215]) by mail.postgresql.org (Postfix) with ESMTP id 2E9ED632A45 for ; Wed, 7 Apr 2010 18:40:19 -0300 (ADT) Received: from localhost (localhost [127.0.0.1]) by spinlock.commandprompt.com (Postfix) with ESMTP id BBBD4348036; Wed, 7 Apr 2010 14:40:17 -0700 (PDT) Received: from spinlock.commandprompt.com ([127.0.0.1]) by localhost (spinlock.commandprompt.com.commandprompt.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BuVs2ZWD9P83; Wed, 7 Apr 2010 14:40:17 -0700 (PDT) Received: from [192.168.1.100] (unknown [75.142.159.62]) by spinlock.commandprompt.com (Postfix) with ESMTPSA id 7484E348034; Wed, 7 Apr 2010 14:40:17 -0700 (PDT) Subject: Re: Occasional giant spikes in CPU load From: "Joshua D. Drake" Reply-To: jd@commandprompt.com To: Craig James Cc: pgsql-performance@postgresql.org In-Reply-To: <4BBCFB12.1010306@emolecules.com> References: <4BBCFB12.1010306@emolecules.com> Content-Type: text/plain; charset="UTF-8" Organization: Command Prompt, Inc. Date: Wed, 07 Apr 2010 14:40:10 -0700 Message-ID: <1270676410.19131.21.camel@jd-desktop.unknown.charter.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.74 tagged_above=-10 required=5 tests=BAYES_20=-0.74 X-Spam-Level: X-Archive-Number: 201004/73 X-Sequence-Number: 38323 On Wed, 2010-04-07 at 14:37 -0700, Craig James wrote: > Most of the time Postgres runs nicely, but two or three times a day we get a huge spike in the CPU load that lasts just a short time -- it jumps to 10-20 CPU loads. Today it hit 100 CPU loads. Sometimes days go by with no spike events. During these spikes, the system is completely unresponsive (you can't even login via ssh). > > I managed to capture one such event using top(1) with the "batch" option as a background process. See output below - it shows 19 active postgress processes, but I think it missed the bulk of the spike. What does iostat 5 say during the jump? Joshua D. Drake -- PostgreSQL.org Major Contributor Command Prompt, Inc: http://www.commandprompt.com/ - 503.667.4564 Consulting, Training, Support, Custom Development, Engineering Respect is earned, not gained through arbitrary and repetitive use or Mr. or Sir.