Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1TjaB9-0006ON-IJ for pgsql-performance@arkaria.postgresql.org; Fri, 14 Dec 2012 18:40:11 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.72) (envelope-from ) id 1TjaB8-0006CS-Qi for pgsql-performance@arkaria.postgresql.org; Fri, 14 Dec 2012 18:40:10 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1TjaB7-0006BR-Bd for pgsql-performance@postgresql.org; Fri, 14 Dec 2012 18:40:09 +0000 Received: from smtp.01.com ([199.36.142.181]) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1TjaB4-0002jt-TN for pgsql-performance@postgresql.org; Fri, 14 Dec 2012 18:40:09 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp-out-2.01.com (Postfix) with ESMTP id 8B90D3900D9 for ; Fri, 14 Dec 2012 12:40:05 -0600 (CST) X-Virus-Scanned: amavisd-new at smtp-out-2.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-2.01.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1UOGsU6-LTHy for ; Fri, 14 Dec 2012 12:40:05 -0600 (CST) Received: from smtp.01.com (localhost.localdomain [127.0.0.1]) by smtp-out-2.01.com (Postfix) with ESMTP id 67275390105 for ; Fri, 14 Dec 2012 12:40:05 -0600 (CST) Received: from [192.168.10.146] (cpe-098-027-058-255.nc.res.rr.com [98.27.58.255]) by smtp-out-2.01.com (Postfix) with ESMTPSA id 159373900D9 for ; Fri, 14 Dec 2012 12:40:04 -0600 (CST) Message-ID: <50CB7284.3020008@pgexperts.com> Date: Fri, 14 Dec 2012 13:40:04 -0500 From: Andrew Dunstan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: pgsql-perform Subject: backend suddenly becomes slow, then remains slow Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -1.9 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org 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? cheers andrew -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance