Re: Introduce wait_for_subscription_sync for TAP tests

Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> writes:
> On Fri, Sep 9, 2022 at 11:31 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Recently a number of buildfarm animals have failed at the same
>> place in src/test/subscription/t/100_bugs.pl [1][2][3][4]:
>>
>> # Failed test '2x3000 rows in t'
>> # at t/100_bugs.pl line 149.
>> # got: '9000'
>> # expected: '6000'
>> # Looks like you failed 1 test of 7.
>> [09:30:56] t/100_bugs.pl ......................
>>
>> This was the last commit to touch that test script. I'm thinking
>> maybe it wasn't adjusted quite correctly? On the other hand, since
>> I can't find any similar failures before the last 48 hours, maybe
>> there is some other more-recent commit to blame. Anyway, something
>> is wrong there.

> It seems that this commit is innocent as it changed only how to wait.

Yeah. I was wondering if it caused us to fail to wait somewhere,
but I concur that's not all that likely.

> It's likely that the commit f6c5edb8abcac04eb3eac6da356e59d399b2bcef
> is relevant.

Noting that the errors have only appeared in the past couple of
days, I'm now suspicious of adb466150b44d1eaf43a2d22f58ff4c545a0ed3f
(Fix recovery_prefetch with low maintenance_io_concurrency).

regards, tom lane