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

06.02.2024 09:48, Amit Kapila wrote:
> cool, is it possible to see whether this patch changes the runtime of
> this test in any noticeable way?
>

Yes, unfortunately it does.
I've measured duration of 100 tests runs without the patch (with pristine
bgwriter and with NO_TEMP_INSTALL):
real    6m46,031s
real    6m52,406s
real    6m51,014s

But with the patched test, I've got:
real    9m39,872s
real    9m40,044s
real    9m38,236s
(nearly 2 seconds increase per one test run)

Under Valgrind, the original test run takes:
Files=1, Tests=36, 334 wallclock secs ( 0.02 usr  0.00 sys + 163.14 cusr  7.98 csys = 171.14 CPU)

But the patched one:
Files=1, Tests=36, 368 wallclock secs ( 0.02 usr  0.00 sys + 182.16 cusr  8.90 csys = 191.08 CPU)
(30 seconds increase)

Maybe the more CPU-efficient solution would be disabling bgworker, as was
proposed in another discussion of tests instability:
https://www.postgresql.org/message-id/ZaTxhjnPygOdosJ4%40ip-10-97-1-34.eu-west-3.compute.internal

Though I think that devising a way to control bgwriter may take more time
than we can afford given the current 031 failure rate on the buildfarm
(17 failures for the last 3 days).

Best regards,
Alexander