Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 3E0442E01F0 for ; Sat, 23 Feb 2008 15:39:23 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 89333-01-3 for ; Sat, 23 Feb 2008 15:39:20 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id C8BF92E02BA for ; Sat, 23 Feb 2008 15:35:38 -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 m1NJZZjZ005577; Sat, 23 Feb 2008 14:35:35 -0500 (EST) To: Joel Stevenson cc: pgsql-performance@postgresql.org Subject: Re: LISTEN / NOTIFY performance in 8.3 In-reply-to: References: Comments: In-reply-to Joel Stevenson message dated "Sat, 23 Feb 2008 10:48:56 -0800" Date: Sat, 23 Feb 2008 14:35:35 -0500 Message-ID: <5576.1203795335@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200802/301 X-Sequence-Number: 28843 Joel Stevenson writes: > I have an existing app that provides a producer / consumer type of > queue and that uses the LISTEN / NOTIFY mechanism to signal the > consumers of new items arriving in the queue. The consumers then > process these items and issue a notify to signal that they have been > processed. In the past issuing these notifications happened very > quickly, now on 8.3 I'm seeing all of them taking over 300ms and many > of them taking 1500ms or more! That's strange, I would not have thought that listen/notify behavior would change at all. How are you measuring this delay exactly? Can you put together a self-contained test case? regards, tom lane