Re: Refactor recovery conflict signaling a little

On 07/03/2026 13:00, Alexander Lakhin wrote:
> Hello Xuneng and Heikki,
>
> 04.03.2026 07:33, Xuneng Zhou wrote:
>>> 03.03.2026 17:39, Heikki Linnakangas wrote:
>>>> On 24/02/2026 10:00, Alexander Lakhin wrote:
>>>>> The "terminating process ..." message doesn't appear when the test passes
>>>>> successfully.
>>>> Hmm, right, looks like something wrong in signaling the recovery conflict. I can't tell if the signal is being sent,
>>>> or it's not processed correctly. Looking at the code, I don't see anything wrong.
>>>>
>> I was unable to reproduce the issue on an x86_64 Linux machine using
>> the provided script. All test runs completed successfully without any
>> failures.
>
> I've added debug logging (see attached) and saw the following:
> !!!SignalRecoveryConflict[282363]
> !!!ProcArrayEndTransaction| pendingRecoveryConflicts = 0
> !!!ProcessInterrupts[283863]| MyProc->pendingRecoveryConflicts: 0
> !!!ProcessInterrupts[283863]| MyProc->pendingRecoveryConflicts: 0
> 2026-03-07 12:21:24.544 EET walreceiver[282421] FATAL:  could not
> receive data from WAL stream: server closed the connection unexpectedly
>         This probably means the server terminated abnormally
>         before or while processing the request.
> 2026-03-07 12:21:24.645 EET postmaster[282355] LOG:  received immediate
> shutdown request
> 2026-03-07 12:21:24.647 EET postmaster[282355] LOG:  database system is
> shut down

A-ha! So MyProc->pendingRecoveryConflicts is being cleared by
ProcArrayEndTransaction(). If I add a small pg_usleep() to the top of
ProcArrayEndTransaction(), I can readily reproduce this.

Thanks for narrowing this down. The attached patch fixes it.

- Heikki