Date: Tue, 13 Aug 2019 17:04:35 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: subscriptionCheck failures on nightjar
Message-ID: <20190813080435.GL2551@paquier.xyz>
References: <20190213171101.6wpz7tardp3t3uvk@alap3.anarazel.de>
 <29708.1550079455@sss.pgh.pa.us>
 <20190213174151.mfylkessxmapt4io@alap3.anarazel.de>
 <30608.1550080759@sss.pgh.pa.us>
 <20190213181225.fathyapig4sm4exa@alap3.anarazel.de>
 <31663.1550082243@sss.pgh.pa.us>
 <20190213183303.ns54frt7cmvo6pgg@alap3.anarazel.de>
 <1466.1550085086@sss.pgh.pa.us>
 <CAEepm=0wB7vgztC5sg2nmJ-H3bnrBT5GQfhUzP+Ffq-WT3g8VA@mail.gmail.com>
 <20190213215147.cjbymfojf6xndr4t@alap3.anarazel.de>
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On Wed, Feb 13, 2019 at 01:51:47PM -0800, Andres Freund wrote:
> I'm not yet sure that that's actually something that's supposed to
> happen, I got to spend some time analysing how this actually
> happens. Normally the contents of the slot should actually prevent it
> from being removed (as they're newer than
> ReplicationSlotsComputeLogicalRestartLSN()). I kind of wonder if that's
> a bug in the drop logic in newer releases.

In the same context, could it be a consequence of 9915de6c which has
introduced a conditional variable to control slot operations?  This
could have exposed more easily a pre-existing race condition.
--
Michael

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