From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: YA race condition in 001_stream_rep.pl (was Re: pgsql: Allow using the updated tuple while moving it to a different par)
Date: Wed, 18 Jul 2018 17:42:40 -0400
Message-ID: <5237.1531950160@sss.pgh.pa.us> (raw)
In-Reply-To: <CAA4eK1LHrn2TNXUU7n-uMENBxkgepe15DG8+eGehG+eWVKF7ag@mail.gmail.com>
References: <E1fdW6s-00054K-QA@gemulon.postgresql.org>
<20180712075909.GG7352@paquier.xyz>
<CAA4eK1L7T-CGTLM+hUq=zGUUaN28Yk0nzWjm0MceO7y9xA5Bhg@mail.gmail.com>
<11887.1531432634@sss.pgh.pa.us>
<1922.1531592205@sss.pgh.pa.us>
<CAA4eK1LHrn2TNXUU7n-uMENBxkgepe15DG8+eGehG+eWVKF7ag@mail.gmail.com>
Amit Kapila <amit.kapila16@gmail.com> writes:
> On Sat, Jul 14, 2018 at 11:46 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> So the issue boils down to this: the test script is, effectively,
>> assuming that it's guaranteed that the walreceiver will send a feedback
>> message before it shuts down; but there is no such guarantee. Is this
>> a bug in the test script, or a bug in the walreceiver logic? I can
>> see the value of having such a guarantee, but I also think it would be
>> nigh impossible to make it a bulletproof guarantee. We could perhaps
>> add "XLogWalRcvSendHSFeedback(true)" somewhere closer to process exit,
>> but that might add more failure modes than it removes.
>>
>> Or we could change the test script to wait for feedback before it
>> issues the shutdown, but then I think the test is a bit pointless.
We've seen two more instances of this failure in the buildfarm since
this exchange (dragonet and flaviventris --- seems like Andres' menagerie
is particularly prone to it).
> Currently, neither the code nor our documentation suggests that we can
> expect HSFeedback before the shutdown, so it is better to adjust the
> test. If the sole purpose of the test is to test feedback after
> shutdown, then it is worth considering to remove the test altogether.
Hearing nobody speaking in favor of the other alternatives,
I've removed the test.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, amit.kapila16@gmail.com, michael@paquier.xyz, pgsql-hackers@lists.postgresql.org
Subject: Re: YA race condition in 001_stream_rep.pl (was Re: pgsql: Allow using the updated tuple while moving it to a different par)
In-Reply-To: <5237.1531950160@sss.pgh.pa.us>
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