[pgpool-general: 9389] Re: WARNING: failed to lock semaphore

[Maria Nieva]

------------------------------
Dear Tatsuo,

Thank you for the instructions. I have applied the patch.

Could you please clarify where I can find log entries that would indicate
if `IpcSemaphoreKill` is called? Would I be able to find this information
in the pgpool logs?

Best Regards,
Maria


On Mon, Mar 3, 2025 at 7:26 PM Tatsuo Ishii <ishii at postgresql.org> wrote:

> Hi Maria,
>
> Sure.
>
> Assuming you have the patch at /tmp/log_semaphore_removal.patch
> and you have the source at /somewhere/pgpool-II-4.4.6:
>
> cd /somewhere/pgpool-II-4.4.6
> patch -p1 < ~/log_semaphore_removal.patch
>
> then you can compile and install pgpool as usual.
>
> Let me know if you have further questions.
>
> Best reagards,
> --
> Tatsuo Ishii
> SRA OSS K.K.
> English:
> https://protect2.fireeye.com/v1/url?k=31323334-501cfaeb-3131568e-454455535732-b2e8c335807c32bc&q=1&e=6e191e27-bfb2-4c07-873b-af81e2a9270c&u=http%3A%2F%2Fwww.sraoss.co.jp%2Findex_en%2F
> Japanese:http://www.sraoss.co.jp
>
> > Dear Tatsuo,
> >
> > Thank you for the patch.
> >
> > I apologize for the inconvenience, but could you please provide guidance
> on
> > how to apply the patch to our Pgpool installation? As mentioned
> previously,
> > we installed Pgpool from source.
> >
> > Thank you for your time and assistance.
> >
> > Best Regards,
> > Maria
> >
> >
> >
> > On Sat, Mar 1, 2025 at 6:12 AM Tatsuo Ishii <ishii at postgresql.org>
> wrote:
> >
> >> Hi Maria,
> >>
> >> > Dear Tatsuo,
> >> >
> >> > Thank you for your response.
> >> >
> >> > I understand your point regarding the semaphore acquisition. However,
> I
> >> > would like to clarify that the semaphore error does not occur
> immediately
> >> > after startup. In our experience, the error manifests itself after
> weeks
> >> of
> >> > running Pgpool. This behavior has been observed in both our staging
> and
> >> > production environments.
> >> >
> >> > If the semaphore configuration is established during Pgpool startup,
> it
> >> > seems unusual that it would change weeks later. Could you please
> >> elaborate
> >> > on what might cause such a delayed configuration change?
> >>
> >> Ok, the semaphore is definitely created at the start up of pgpool. It
> >> should never been removed until pgpool shuts down. If it's removed,
> >> that must be a bug of pgpool. There's only 1 place where semaphore is
> >> removed (IpcSemaphoreKill). Can you apply attached patch to confirm
> >> the function is actually called? If you find semaphore is removed but
> >> IpcSemaphoreKill is not called, then the semaphore was removed by
> >> someone else.
> >>
> >> Best reagards,
> >> --
> >> Tatsuo Ishii
> >> SRA OSS K.K.
> >> English:
> >>
> https://protect2.fireeye.com/v1/url?k=31323334-501cfaeb-3131568e-454455535732-b2e8c335807c32bc&q=1&e=af34ac69-01a0-4305-af59-968a7ca1f337&u=http%3A%2F%2Fwww.sraoss.co.jp%2Findex_en%2F
> >> Japanese:http://www.sraoss.co.jp
> >>
> >>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.pgpool.net/pipermail/pgpool-general/attachments/20250306/afc6c5a6/attachment.htm>