| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com> |
| Cc: | Justin Pryzby <pryzby(at)telsasoft(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: pg14b1 stuck in lazy_scan_prune/heap_page_prune of pg_statistic |
| Date: | 2021-06-06 17:59:10 |
| Message-ID: | 657425.1623002350@sss.pgh.pa.us |
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Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com> writes:
> On Sun, 6 Jun 2021 at 18:35, Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
>> However, I also found an autovacuum chewing 100% CPU, and it appears the
>> problem is actually because autovacuum has locked a page of pg-statistic, and
>> every other process then gets stuck waiting in the planner. I checked a few
>> and found these:
> My suspicion is that for some tuple on that page
> HeapTupleSatisfiesVacuum() returns HEAPTUPLE_DEAD for a tuple that it
> thinks should have been cleaned up by heap_page_prune, but isn't. This
> would result in an infinite loop in lazy_scan_prune where the
> condition on vacuumlazy.c:1800 will always be true, but the retry will
> not do the job it's expected to do.
Since Justin's got a debugger on the process already, it probably
wouldn't be too hard to confirm or disprove that theory by stepping
through the code.
regards, tom lane
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