Message-ID: <16cdffd4-f06c-4957-9132-1849a719f3d4@postgrespro.ru>
Date: Mon, 22 Jun 2026 21:32:50 +0300
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Subject: Re: Deadlock detector fails to activate on a hot standby replica
To: Fujii Masao <masao.fujii@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
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From: Vitaly Davydov <v.davydov@postgrespro.ru>
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Dear Fujii Masao, All

While working on porting the patch to other majors, I've found that, the code
in RegisterPinCountWaiter() (see below) should be improved because it doesn't 
unlock the bufHdr when the error is raised, as in LockBufferForCleanup().
I guess it works, but it keeps the locks a bit longer.

RegisterPinCountWaiter v5 patch code:
     ...
     if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
	    bufHdr->wait_backend_pgprocno != MyProcNumber)
	    elog(ERROR, "multiple processes attempting to wait for pincount 1");

RegisterPinCountWaiter proposed changes:
     ...
     if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
	    bufHdr->wait_backend_pgprocno != MyProcNumber)
	{
	    UnlockBufHdr(bufHdr);
	    elog(ERROR, "multiple processes attempting to wait for pincount 1");
	}

What do you think?

With best regards,
Vitaly