Re: Why is subscription/t/031_column_list.pl failing so much?

On Tue, 6 Feb 2024 at 08:30, Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
>
> Hello Amit,
>
> 05.02.2024 15:20, Amit Kapila wrote:
> > If this can be reproduced frequently then we can even try to test the
> > patch in that thread by Osumi-San [1] (I haven't tested that it
> > applies cleanly but shouldn't be difficult to make it work) based on
> > the theory that walsender is starting up at an LSN somewhere before
> > where the publication is created.
> >
> > [1] - https://www.postgresql.org/message-id/TYCPR01MB83737A68CD5D554EA82BD7B9EDD39%40TYCPR01MB8373.jpnprd01.prod.outlook.com
> >
>
> Yes, with the aforementioned modification of bgwriter.c and when running
> 20 tests in parallel, I got failures on iterations 20. 3, 21 ..., but with the
> updated Osumi-San's patch (which adds wait_for_catchup('sub1') before every
> ALTER SUBSCRIPTION sub1 SET PUBLICATION ...) applied, 300 iterations ran
> with no failures.

I was able to reproduce the issue with the patch changes suggested in
bgwriter, but for me it failed in the 287th run.
Then I had run the test 1000 times with the test changes shared at [1]
and the test had passed all the 1000 times successfully.

I have measured the test execution with average of 10 runs and found
that it takes about 1.2 seconds more time to execute with the changes:
Without patch: 8.454 seconds
With test change patch: 9.672 seconds

For the test execution comparison I had used a machine which has total
Memory of 755.536 GB, 120 CPUs and RHEL 7 Operating System.

[1] - https://www.postgresql.org/message-id/e6ce3cf7-4025-f129-e3ac-0f778469f720%40gmail.com

Regards,
Vignesh