Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 7E46F1337999 for ; Wed, 29 Dec 2010 15:59:07 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 20199-02 for ; Wed, 29 Dec 2010 19:59:00 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id 35DED133616B for ; Wed, 29 Dec 2010 15:59:00 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id oBTJwxeu000305; Wed, 29 Dec 2010 14:58:59 -0500 (EST) To: Craig James cc: pgsql-performance@postgresql.org Subject: Re: long wait times in ProcessCatchupEvent() In-reply-to: <4D1B8BD9.4060105@emolecules.com> References: <4D1B8BD9.4060105@emolecules.com> Comments: In-reply-to Craig James message dated "Wed, 29 Dec 2010 11:28:25 -0800" Date: Wed, 29 Dec 2010 14:58:59 -0500 Message-ID: <304.1293652739@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201012/329 X-Sequence-Number: 41781 Craig James writes: > On 12/29/10 6:28 AM, Julian v. Bock wrote: >> I have the problem that on our servers it happens regularly under a >> certain workload (several times per minute) that all backend processes >> get a SIGUSR1 and spend several seconds in ProcessCatchupEvent(). > This sounds like the exact same problem I had on Postgres 8.3 and 8.4: > http://archives.postgresql.org/pgsql-performance/2010-04/msg00071.php > Updating to Postgres version 9 fixed it. Here is what appeared to be the best analysis of what was happening, but we never confirmed it. > http://archives.postgresql.org/pgsql-performance/2010-06/msg00464.php It happened for you on 8.4 too? In that previous thread you were still on 8.3. If you did see it on 8.4 then it wasn't sinval ... regards, tom lane