Re: Testing autovacuum wraparound (including failsafe)

Hello Masahiko-san,

01.12.2023 05:14, Masahiko Sawada wrote:
> FYI I've configured the buildfarm animal perentie to run regression
> tests including xid_wraparound:
>
> https://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=perentie&br=HEAD

Please look at a failure produced by perentie recently: [1].

I've analyzed all the available detailed perentie logs (starting from
2024-04-04) and got the following durations of the pg_ctl stop operation
at the end of the 001_emergency_vacuum.pl (from the
module-xid_wraparound-check stage): see perentie-timings.txt and
perentie-timings.png attached. So it looks like perentie needs larger
PGCTLTIMEOUT for the test (maybe 180 seconds would work?).

Though it's not clear to me, why this test takes so long on that animal,
even when it succeeds. For example, [2] shows:
[09:28:23] t/001_emergency_vacuum.pl .. ok   225894 ms ( 0.00 usr 0.00 sys +  0.31 cusr  0.43 csys =  0.74 CPU)
[09:30:53] t/002_limits.pl ............ ok   150291 ms ( 0.00 usr 0.00 sys +  1.85 cusr  1.50 csys =  3.35 CPU)
[09:49:33] t/003_wraparounds.pl ....... ok  1119766 ms ( 0.00 usr 0.00 sys +  1.68 cusr  2.39 csys =  4.07 CPU)

While what I'm seeing locally on my Fedora 40 VM is:
PG_TEST_EXTRA="xid_wraparound" make -s check -C src/test/modules/xid_wraparound/ PROVE_FLAGS="--timer"
# +++ tap check in src/test/modules/xid_wraparound +++
[04:41:56] t/001_emergency_vacuum.pl .. ok    18852 ms ( 0.01 usr 0.00 sys +  0.14 cusr  0.28 csys =  0.43 CPU)
[04:42:15] t/002_limits.pl ............ ok    18539 ms ( 0.00 usr 0.00 sys +  0.72 cusr  0.88 csys =  1.60 CPU)
[04:42:34] t/003_wraparounds.pl ....... ok    74368 ms ( 0.00 usr 0.00 sys +  0.82 cusr  2.57 csys =  3.39 CPU)

Also, maybe it would make sense to run this test for REL_17_STABLE too, as
dodo is not with us since 2024-09-04, and I don't know if there are other
animals running these tests (having xid_wraparound in PG_TEST_EXTRA).

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=perentie&dt=2024-10-05%2000%3A00%3A14
[2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=perentie&dt=2024-10-06%2000%3A00%3A13

Best regards,
Alexander