From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Noah Misch <noah@leadboat.com>,
        Petr Jelinek <petr.jelinek@2ndquadrant.com>,
        Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
        Erik Rijkers <er@xs4all.nl>, David Steele <david@pgmasters.net>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>,
        Robert Haas <robertmhaas@gmail.com>,
        Craig Ringer <craig@2ndquadrant.com>,
        pgsql-hackers-owner@postgresql.org
Subject: Re: snapbuild woes
In-reply-to: <20170501160918.j27fvngzuwspg7d6@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 01 May 2017 09:09:18 -0700"
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Date: Mon, 01 May 2017 12:32:07 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2017-05-01 08:46:47 -0400, Tom Lane wrote:
>> 30sec is kind of a big lump from a buildfarm standpoint, especially if
>> you mean "it runs for 30s on my honkin' fast workstation".  I'm fine
>> with individual tests that run for ~ 1sec.

> I was more thinking of pgench -T$XX, rather than constant number of
> iterations.  I currently can reproduce the issues within like 3-4
> minutes, so 5s is probably not quite sufficient to get decent coverage.

Adding a five-minute pgbench run to the buildfarm sequence is definitely
going to get you ridden out of town on a rail.  But quite aside from the
question of whether we can afford the cycles, it seems like the wrong
approach.  IMO the buildfarm is mainly for verifying portability, not for
trying to prove that race-like conditions don't exist.  In most situations
we're going out of our way to ensure reproduceability of tests we add to
the buildfarm sequence; but it seems like this is looking for
irreproducible results.

			regards, tom lane


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