Re: Transaction timeout

On Fri, Dec 22, 2023 at 10:25 PM Japin Li <japinli@hotmail.com> wrote:
>
>
> On Fri, 22 Dec 2023 at 20:29, Junwang Zhao <zhjwpku@gmail.com> wrote:
> > On Fri, Dec 22, 2023 at 1:39 PM Japin Li <japinli@hotmail.com> wrote:
> >>
> >>
> >> On Tue, 19 Dec 2023 at 22:06, Japin Li <japinli@hotmail.com> wrote:
> >> > On Tue, 19 Dec 2023 at 18:27, Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> >> >>> On 19 Dec 2023, at 13:26, Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> >> >>>
> >> >>> I don’t have Windows machine, so I hope CF bot will pick this.
> >> >>
> >> >> I used Github CI to produce version of tests that seems to be is stable on Windows.
> >> >
> >> > It still failed on Windows Server 2019 [1].
> >> >
> >> > diff -w -U3 C:/cirrus/src/test/isolation/expected/timeouts.out C:/cirrus/build/testrun/isolation/isolation/results/timeouts.out
> >> > --- C:/cirrus/src/test/isolation/expected/timeouts.out        2023-12-19 10:34:30.354721100 +0000
> >> > +++ C:/cirrus/build/testrun/isolation/isolation/results/timeouts.out  2023-12-19 10:38:25.877981600 +0000
> >> > @@ -100,7 +100,7 @@
> >> >  step stt3_check_stt2: SELECT count(*) FROM pg_stat_activity WHERE application_name = 'isolation/timeouts/stt2'
> >> >  count
> >> >  -----
> >> > -    0
> >> > +    1
> >> >  (1 row)
> >> >
> >> >  step itt4_set: SET idle_in_transaction_session_timeout = '1ms'; SET statement_timeout = '10s'; SET lock_timeout = '10s'; SET transaction_timeout = '10s';
> >> >
> >> > [1] https://api.cirrus-ci.com/v1/artifact/task/4707530400595968/testrun/build/testrun/isolation/isolation/regression.diffs
> >>
> >> Hi,
> >>
> >> I try to split the test for transaction timeout, and all passed on my CI [1].
> >>
> >> OTOH, I find if I set transaction_timeout in a transaction, it will not take
> >> effect immediately.  For example:
> >>
> >> [local]:2049802 postgres=# BEGIN;
> >> BEGIN
> >> [local]:2049802 postgres=*# SET transaction_timeout TO '1s';
> > when this execute, TransactionTimeout is still 0, this command will
> > not set timeout
> >> SET
> >> [local]:2049802 postgres=*# SELECT relname FROM pg_class LIMIT 1;  -- wait 10s
> > when this command get execute, start_xact_command will enable the timer
>
> Thanks for your exaplantion, got it.
>
> >>    relname
> >> --------------
> >>  pg_statistic
> >> (1 row)
> >>
> >> [local]:2049802 postgres=*# SELECT relname FROM pg_class LIMIT 1;
> >> FATAL:  terminating connection due to transaction timeout
> >> server closed the connection unexpectedly
> >>         This probably means the server terminated abnormally
> >>         before or while processing the request.
> >> The connection to the server was lost. Attempting reset: Succeeded.
> >>
> >> It looks odd.  Does this is expected? I'm not read all the threads,
> >> am I missing something?
> >
> > I think this is by design, if you debug statement_timeout, it's the same
> > behaviour, the timeout will be set for each command after the second
> > command was called, you just aren't aware of this.
> >
>
> I try to set idle_in_transaction_session_timeout after begin transaction,
> it changes immediately, so I think transaction_timeout should also be take
> immediately.

Ah, right, idle_in_transaction_session_timeout is set after the set
command finishes and before the backend send *ready for query*
to the client, so the value of the GUC is already set before
next command.

I bet you must have checked this ;)

>
> > I doubt people will set this in a transaction.
>
> Maybe not,
>
>
> --
> Regrads,
> Japin Li
> ChengDu WenWu Information Technology Co., Ltd.



-- 
Regards
Junwang Zhao