Horton

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

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2024-04-09T18:59:57Z
Lists: pgsql-bugs

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Ensure vacuum removes all visibly dead tuples older than OldestXmin

  2. Combine freezing and pruning steps in VACUUM

  3. Handle non-chain tuples outside of heap_prune_chain()

  4. Fix false reports in pg_visibility

  5. Remove retry loop in heap_page_prune().

  6. vacuumlazy.c: document vistest and OldestXmin.

  7. Deduplicate choice of horizon for a relation procarray.c.

  8. Remove tupgone special case from vacuumlazy.c.

  9. Simplify state managed by VACUUM.

  10. Recycle nbtree pages deleted during same VACUUM.

  11. snapshot scalability: Don't compute global horizons while building snapshots.

  12. Raise error when affecting tuple moved into different partition.

On Sun, Apr 7, 2024 at 6:00 AM Alexander Lakhin <exclusion@gmail.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