Message-ID: <e3fa725b-474c-c155-6a0d-5c97cbfbdc4a@gmail.com>
Date: Sat, 20 Jul 2024 11:00:00 +0300
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Subject: Re: race condition in pg_class
To: Noah Misch <noah@leadboat.com>
Cc: pgsql-hackers@postgresql.org
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From: Alexander Lakhin <exclusion@gmail.com>
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Hello Noah,

28.06.2024 08:13, Noah Misch wrote:
> Pushed.

A recent buildfarm test failure [1] showed that the
intra-grant-inplace-db.spec test added with 0844b3968 may fail
on a slow machine (per my understanding):

test intra-grant-inplace-db       ... FAILED     4302 ms

@@ -21,8 +21,7 @@
      WHERE datname = current_catalog
          AND age(datfrozenxid) > (SELECT min(age(x)) FROM frozen_witness);

-?column?
-----------------------
-datfrozenxid retreated
-(1 row)
+?column?
+--------
+(0 rows)

whilst the previous (successful) run shows much shorter duration:
test intra-grant-inplace-db       ... ok          540 ms

I reproduced this failure on a VM slowed down so that the test duration
reached 4+ seconds, with 100 test: intra-grant-inplace-db in
isolation_schedule:
test intra-grant-inplace-db       ... ok         4324 ms
test intra-grant-inplace-db       ... FAILED     4633 ms
test intra-grant-inplace-db       ... ok         4649 ms

But as the test going to be modified by the inplace110-successors-v8.patch
and the modified test (with all three latest patches applied) passes
reliably in the same conditions, maybe this failure doesn't deserve a
deeper exploration.

What do you think?

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=habu&dt=2024-07-18%2003%3A08%3A08

Best regards,
Alexander