Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id AE6149FB4F1 for ; Fri, 27 Jul 2007 05:58:16 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 63750-01 for ; Fri, 27 Jul 2007 05:58:06 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from lists.commandprompt.com (host-254.commandprompt.net [207.173.203.254]) by postgresql.org (Postfix) with ESMTP id 2C5CB9FB4DC for ; Fri, 27 Jul 2007 05:58:10 -0300 (ADT) Received: from alvh.no-ip.org ([64.122.184.54]) (authenticated bits=0) by lists.commandprompt.com (8.13.7/8.13.6) with ESMTP id l6R8w5t4020341; Fri, 27 Jul 2007 01:58:05 -0700 Received: by alvh.no-ip.org (Postfix, from userid 1000) id 53A2A4381D9; Fri, 27 Jul 2007 01:58:05 -0700 (PDT) Date: Fri, 27 Jul 2007 04:58:05 -0400 From: Alvaro Herrera To: "Jignesh K. Shah" Cc: Simon Riggs , Tom Lane , Josh Berkus , pgsql-performance@postgresql.org Subject: Re: User concurrency thresholding: where do I look? Message-ID: <20070727085805.GF2550@alvh.no-ip.org> Mail-Followup-To: "Jignesh K. Shah" , Simon Riggs , Tom Lane , Josh Berkus , pgsql-performance@postgresql.org References: <1545.1185214760@sss.pgh.pa.us> <46A7D5AD.9000706@sun.com> <13162.1185405865@sss.pgh.pa.us> <46A8AFDF.3050804@sun.com> <26825.1185460816@sss.pgh.pa.us> <46A8BD62.2080904@sun.com> <1185465076.4190.87.camel@ebony.site> <46A8F9AA.4040507@sun.com> <1185480291.5510.22.camel@ebony.site> <46A90F83.8050401@sun.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46A90F83.8050401@sun.com> User-Agent: Mutt/1.5.16 (2007-06-11) X-Virus-Scanned: ClamAV 0.90.3/3775/Wed Jul 25 22:56:02 2007 on projects.commandprompt.com X-Virus-Status: Clean X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by milter-greylist-1.6 (lists.commandprompt.com [192.168.2.159]); Fri, 27 Jul 2007 01:58:06 -0700 (PDT) X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200707/382 X-Sequence-Number: 26066 Jignesh K. Shah wrote: > Top Wait time seems to come from the following code path for > ProcArrayLock: > > Lock Id Mode Count > ProcArrayLock Exclusive 21 > > Lock Id Combined Time (ns) > ProcArrayLock 5255937500 > > Lock Id Combined Time (ns) > > > postgres`LWLockAcquire+0x1f0 > postgres`CommitTransaction+0x104 Yeah, ProcArrayLock is pretty contended. I think it would be kinda neat if we could split it up in partitions. This lock is quite particular though. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support