Received: from localhost (maia-2.hub.org [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id E712C9FB5B9 for ; Thu, 1 Mar 2007 17:58:25 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-new, port 10024) with ESMTP id 73407-04 for ; Thu, 1 Mar 2007 17:58:18 -0400 (AST) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.4 Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.190]) by postgresql.org (Postfix) with ESMTP id EB7369FB511 for ; Thu, 1 Mar 2007 17:58:21 -0400 (AST) Received: by nf-out-0910.google.com with SMTP id x4so1042742nfb for ; Thu, 01 Mar 2007 13:58:20 -0800 (PST) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=f0QAbwDJiBNqkFVo2BNlpIUaUj73lnSM2N2b2GAeSYCHkA8DD5N0hv9XFuUjjrXQws07VekgJm+Z4PeJiKUNVfzrhbK4b3baqWma2Zo7kClP40x8yc69QUicNcvSMqR61C4cTWL6ca76Fan6HH2jALJ28W8ZSdS1nDpvhdY71Jw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=hmyncbTXHzGKVIUUhRYzg4Hpp93Kh9zCjxeQwJ9Zfv+rXIOHdDD++Dq6RJXovJ/2P2db12Pz7cAtHUGcmniuO+aKxGctafyjIg0BHLk4pWv6YaKJzklJUhsEDWAboEvtjDrq5ROxwIvw1Sif/dFtaIH8T0GWLXX8RNTbP5X7ou0= Received: by 10.78.180.18 with SMTP id c18mr204841huf.1172786300407; Thu, 01 Mar 2007 13:58:20 -0800 (PST) Received: by 10.78.35.18 with HTTP; Thu, 1 Mar 2007 13:58:20 -0800 (PST) Message-ID: Date: Thu, 1 Mar 2007 16:58:20 -0500 From: "Merlin Moncure" To: "Tom Lane" Subject: Re: stats collector process high CPU utilization Cc: "Benjamin Minshall" , pgsql-performance@postgresql.org In-Reply-To: <16282.1172779976@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <45CB5D06.7090004@intellicon.biz> <62089.75.14.32.120.1170994418.squirrel@intellicon.biz> <14668.1170995218@sss.pgh.pa.us> <20070209142459.GB4253@alvh.no-ip.org> <24717.1171033699@sss.pgh.pa.us> <29832.1171036557@sss.pgh.pa.us> <45CCA0DB.2010903@intellicon.biz> <1116.1171038786@sss.pgh.pa.us> <45CCBF13.2000707@intellicon.biz> <16282.1172779976@sss.pgh.pa.us> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.244 tagged_above=0 required=5 tests=AWL, BAYES_05, BIZ_TLD, SPF_PASS X-Spam-Level: X-Archive-Number: 200703/24 X-Sequence-Number: 23429 On 3/1/07, Tom Lane wrote: > Benjamin Minshall writes: > > Tom Lane wrote: > >> It's sounding like what you had was just transient bloat, in which case > >> it might be useful to inquire whether anything out-of-the-ordinary had > >> been done to the database right before the excessive-CPU-usage problem > >> started. > > > I don't believe that there was any unusual activity on the server, but I > > have set up some more detailed logging to hopefully identify a pattern > > if the problem resurfaces. > > A further report led us to realize that 8.2.x in fact has a nasty bug > here: the stats collector is supposed to dump its stats to a file at > most every 500 milliseconds, but the code was actually waiting only > 500 microseconds :-(. The larger the stats file, the more obvious > this problem gets. I think this explains the trigger that was blowing up my FC4 box. merlin