Re: BUG #17257: (auto)vacuum hangs within lazy_scan_prune()

On Sun, Apr 7, 2024 at 6:00 AM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
> I've refreshed the script and simplified it a bit not to use Linux
> specifics.

Thanks. I was able to reproduce this today on macOS 13.6.2 with
REL_14_0. It didn't seem like it reproduced as quickly for me as it
did for you, but I got it to fail an assertion eventually. Then my
debugging efforts were frustrated by
http://postgr.es/m/CA+TgmobW9bEuvSrQR1D1K6_8=DmY2tzkuepAjCWF=j4B1w0rWw@mail.gmail.com
- gah

> But on dad1539ae I got no failures for 3 runs (the same is on
> REL_16_STABLE with a slightly modified lazy_scan_prune patch).

I'm having trouble understanding what this means exactly -- are you
talking about REL_16_STABLE, or about dad1539ae, or both, or what? At
any rate, it's really important here that we understand whether we
still have a bug here, and if so, in which releases and with what test
case. I wasn't aware of dad1539ae but that certainly seems like it
might've made a big difference, if not fixing the problem entirely
then at least making it a lot less likely. And I think it's possible
that some of the related freezing+pruning commits on master might have
removed the problem altogether, but that needs to be tested.

--
Robert Haas
EDB: http://www.enterprisedb.com