Re: Deadlock detector fails to activate on a hot standby replica

On Tue, Aug 4, 2026 at 7:16 PM Vitaly Davydov <v(dot)davydov(at)postgrespro(dot)ru> wrote:
>
> Hi JH Shin,
>
> On 8/4/26 08:30, JoongHyuk Shin wrote:
> > On Thu, Jul 2, 2026 at 12:57 AM Vitaly Davydov <v(dot)davydov(at)postgrespro(dot)ru
> > <mailto:v(dot)davydov(at)postgrespro(dot)ru>> wrote:
> >> It seems, the patch should be completely rewritten. I will try to
> >> prepare a new patch version.
> >
> > Hi Vitaly,
> >
> > Any update on the new version you mentioned in your last message?
>
> I can't give you an exact time right now because of the issues highlighted
> in the last review that need to be elaborated on. Sorry, I've just started
> looking at it again. It might take a week or two. If your patch is ready for
> commit, please go ahead with it. As I see it, the main change in your patch
> avoids periodic message logging by passing the log_recovery_conflict variable
> from the caller. Once your changes are committed, I don't foresee any problems
> merging them into my patch.

Personally, I still think the patch by JoongHyuk should be deferred
until the one in the current thread is applied, because the imagined
race case [1] still seems possible to me in a refreshed look. That
potential race might be fixed in standalone beforehand but the
potential fix seems not elegant to me. Sure the decision of pulling
the trigger or not is up to Fujii-san or other committers. There seems
to be some additional threads/issues piled up in this area [2].
Haven't checked the dependency among them yet. I'd like to help if you
don't have time, but I won't be able to do so in this or next week
since I've been wrestling with some subtle bugs which better be
reported/fixed before the upcoming GA.

[1] https://www.postgresql.org/message-id/CABPTF7VCdsfmvZpvXtuNHYhBYK4ivnfPAAM=vFXsgqYv2p2eyA@mail.gmail.com
[2] https://www.postgresql.org/message-id/CAHg+QDf3NcB3vOAqQ5EFcV5DYYUZ9snCSJAU-x1JDbtcjK3eBQ@mail.gmail.com

--
Regards,
Xuneng Zhou
HighGo Software Co., Ltd.