To: Richard Huxton <dev@archonet.com>
cc: "Craig A. James" <cjames@modgraph-usa.com>,
	Russell Smith <mr-russ@pws.com.au>, pgsql-performance@postgresql.org
Subject: Re: Postgres server crash 
In-reply-to: <455CA016.7030709@archonet.com> 
References: <ce4072df0610201305u7836dc7bn437ec0aaf1c3e25f@mail.gmail.com>
	<b42b73150610201811m84369f7kc7d58b39aed3ad73@mail.gmail.com>
	<ce4072df0610230810t5d66bbb8xf1e9c0ed71b6b6c0@mail.gmail.com>
	<20061023215913.GW26892@nasby.net>
	<ce4072df0610240617s72f35540odd3d4e0903313b63@mail.gmail.com>
	<20061025001709.GA26892@nasby.net>
	<453EF7C4.2040105@modgraph-usa.com>
	<455BCAE8.8010905@modgraph-usa.com>
	<455BCCCD.2020701@pws.com.au> <455C420D.8090209@archonet.com>
	<455C9CCA.7080804@modgraph-usa.com> <455CA016.7030709@archonet.com>
Comments: In-reply-to Richard Huxton <dev@archonet.com>
	message dated "Thu, 16 Nov 2006 17:29:58 +0000"
Date: Thu, 16 Nov 2006 13:10:31 -0500
Message-ID: <19528.1163700631@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Richard Huxton <dev@archonet.com> writes:
> Craig A. James wrote:
>> It can't be a coincidence that these were the only two processes in a 
>> SELECT operation.  Does the server disable signals at critical points?

> If a "kill -9" as root doesn't get rid of them, I think I'm right in 
> saying that it's a kernel-level problem rather than something else.

I didn't actually see Craig say anywhere that he'd tried "kill -9" on
those backends.  If he did and it didn't do anything, then clearly they
were in some kind of uninterruptable wait, which is certainly evidence
of a kernel or hardware issue.  If he didn't do "kill -9" then we don't
really know what the issue was --- it's not improbable that they were
stuck in some loop not containing a CHECK_FOR_INTERRUPTS() test.

			regards, tom lane