Re: Vacuum ERRORs out considering freezing dead tuples from before OldestXmin

Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> On Sun, Jul 21, 2024 at 12:51 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I do not think the answer to this is to nag the respective animal
>> owners to raise PG_TEST_TIMEOUT_DEFAULT. IMV this test is simply
>> not worth the cycles it takes, at least not for these machines.

> Can't we just move it to PG_TEST_EXTRA? Alongside the existing
> "xid_wraparound" test?

Perhaps. xid_wraparound seems entirely too slow for what it's
testing as well, if you ask me, and there's a concurrent thread
about that test causing problems too.

> There will always be a small number of extremely slow buildfarm
> animals. Optimizing for things like Raspberry pi animals with SD cards
> just doesn't seem like a good use of developer time. I really care
> about keeping the tests fast, but only on platforms that hackers
> actually use for their development work.

I find this argument completely disingenuous. If a test is slow
enough to cause timeout failures on slower machines, then it's also
eating a disproportionate number of cycles in every other check-world
run --- many of which have humans waiting for them to finish. Caring
about the runtime of test cases is good for future-you not just
obsolete buildfarm animals.

I note also that the PG_TEST_EXTRA approach has caused xid_wraparound
to get next-to-zero buildfarm coverage. If that test is actually
capable of revealing problems, we're unlikely to find out under the
status quo.

regards, tom lane