From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Unexpected "shared memory block is still in use"
Date: Fri, 10 May 2019 10:55:41 -0400
Message-ID: <25485.1557500141@sss.pgh.pa.us> (raw)
In-Reply-To: <20190510072213.GA1098093@rfd.leadboat.com>
References: <22224.1557340366@sss.pgh.pa.us>
<20190509055414.GB1066859@rfd.leadboat.com>
<2663.1557409654@sss.pgh.pa.us>
<2226.1557439179@sss.pgh.pa.us>
<17642.1557442078@sss.pgh.pa.us>
<20190510072213.GA1098093@rfd.leadboat.com>
Noah Misch <noah@leadboat.com> writes:
> Looks good. That is basically a defect in commit c09850992; the race passed
> from irrelevance to relevance when that commit subjected more segments to the
> test. Thanks for diagnosing it.
The bug's far older than that, surely, since before c09850992 we treated
*any* shmat failure as meaning we'd better fail. I think you're right
that c09850992 might've made it slightly more probable, but most likely
the bottom line here is just that we haven't been doing parallel
check-worlds a lot until relatively recently. The buildfarm would be
kind of unlikely to hit this I think --- AFAIK it doesn't launch multiple
postmasters using the same port number concurrently. But parallel
invocation of TAP test scripts makes the hazard real.
Will go fix/backpatch in a minute.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, noah@leadboat.com, pgsql-hackers@lists.postgresql.org
Subject: Re: Unexpected "shared memory block is still in use"
In-Reply-To: <25485.1557500141@sss.pgh.pa.us>
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