Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1X1jV4-0000rS-IK for pgsql-performance@arkaria.postgresql.org; Mon, 30 Jun 2014 21:52:34 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1X1jV3-00073i-9M for pgsql-performance@arkaria.postgresql.org; Mon, 30 Jun 2014 21:52:33 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1X1jV2-00073Z-Fb for pgsql-performance@postgresql.org; Mon, 30 Jun 2014 21:52:32 +0000 Received: from smtp128.ord.emailsrvr.com ([173.203.6.128]) by magus.postgresql.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1X1jUy-0002DG-4i for pgsql-performance@postgresql.org; Mon, 30 Jun 2014 21:52:30 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp25.relay.ord1a.emailsrvr.com (SMTP Server) with ESMTP id 7B92E3803F9; Mon, 30 Jun 2014 17:52:25 -0400 (EDT) X-Virus-Scanned: OK Received: by smtp25.relay.ord1a.emailsrvr.com (Authenticated sender: jeff.frost-AT-pgexperts.com) with ESMTPSA id 39C6138053F; Mon, 30 Jun 2014 17:52:24 -0400 (EDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_C37BD7DB-3A2E-4B60-BDE4-3FC324BC0492" Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Subject: Re: Postgres Replaying WAL slowly From: Jeff Frost In-Reply-To: <2E438E7D-E3C1-47A1-A1AF-9FE50A14A302@pgexperts.com> Date: Mon, 30 Jun 2014 14:52:22 -0700 Cc: Andres Freund , Matheus de Oliveira , Soni M , Heikki Linnakangas , pgsql-performance Message-Id: <571D044B-260A-4E06-ACBC-8869B8F73C0F@pgexperts.com> References: <20140630171416.GK21422@awork2.anarazel.de> <8DA8C140-818D-4184-AAE6-CA37278B983C@pgexperts.com> <20140630183908.GT26930@awork2.anarazel.de> <0A7B96D4-DB10-49A8-A268-F28960F2E137@pgexperts.com> <20300.1404156750@sss.pgh.pa.us> <20140630201523.GV26930@awork2.anarazel.de> <943ECC8E-8899-422E-937C-50DE20E1F7AC@pgexperts.com> <21474.1404160784@sss.pgh.pa.us> <2E438E7D-E3C1-47A1-A1AF-9FE50A14A302@pgexperts.com> To: Tom Lane X-Mailer: Apple Mail (2.1878.2) X-Pg-Spam-Score: -2.6 (--) 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 --Apple-Mail=_C37BD7DB-3A2E-4B60-BDE4-3FC324BC0492 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Jun 30, 2014, at 1:46 PM, Jeff Frost wrote: >> So it seems like we have a candidate explanation. I'm a bit = surprised >> that StandbyReleaseLocks would get this slow if there are only a = dozen >> AccessExclusiveLocks in place at any one time, though. Perhaps that >> was a low point and there are often many more? >>=20 >> =09 >=20 > Entirely possible that it was a low point. We'll set up some = monitoring to track the number of AccessExclusiveLocks and see how much = variance there is throughout the day. Since we turned on the monitoring for that, we had a peak of 13,550 = AccessExclusiveLocks. So far most of the samples have been in the = double digit, with that and two other outliers: 6,118 and 12,747.= --Apple-Mail=_C37BD7DB-3A2E-4B60-BDE4-3FC324BC0492 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
On Jun 30, 2014, at 1:46 PM, Jeff = Frost <jeff@pgexperts.com>= wrote:

So it seems like we have a candidate explanation.  I'm a bit = surprised
that StandbyReleaseLocks would get this slow if there are = only a dozen
AccessExclusiveLocks in place at any one time, though. =  Perhaps that
was a low point and there are often many = more?

=

Entirely possible that it was a low point.  We'll set = up some monitoring to track the number of AccessExclusiveLocks and see = how much variance there is throughout the day.


Since we turned on the = monitoring for that, we had a peak of 13,550 AccessExclusiveLocks. =  So far most of the samples have been in the double digit, with = that and two other outliers: 6,118 and 12,747.
= --Apple-Mail=_C37BD7DB-3A2E-4B60-BDE4-3FC324BC0492--