Re: Simplify backend terminate and wait logic in postgres_fdw test

On Thu, Apr 8, 2021 at 5:28 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>
> On Thu, Apr 08, 2021 at 04:55:22PM +0530, Bharath Rupireddy wrote:
> > With the recent commit aaf0432572 which introduced a waiting/timeout
> > capability for pg_teriminate_backend function, I would like to do
> > $subject. Attaching a patch, please have a look.
>
> +-- Terminate the remote backend having the specified application_name and wait
> +-- for the termination to complete. 10 seconds timeout here is chosen randomly,
> +-- we will see a warning if the process doesn't go away within that time.
> +SELECT pg_terminate_backend(pid, 10000) FROM pg_stat_activity
> + WHERE application_name = 'fdw_retry_check';
>
> I think that you are making the tests less stable by doing that. A
> couple of buildfarm machines are very slow, and 10 seconds would not
> be enough. So it seems to me that this patch is trading what is a
> stable solution for a solution that may finish by randomly bite.

Agree. Please see the attached patch, I removed a fixed waiting time.
Instead of relying on pg_stat_activity, pg_sleep and
pg_stat_clear_snapshot, now it depends on pg_terminate_backend and
pg_wait_for_backend_termination. This way we could reduce the
functions that the procedure terminate_backend_and_wait uses and also
the new functions pg_terminate_backend and
pg_wait_for_backend_termination gets a test coverage.

Thoughts?

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com