Horton

Re: Intermittent buildfarm failures on wrasse

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, Noah Misch <noah@leadboat.com>, David Rowley <dgrowleyml@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-04-14T22:28:34Z
Lists: pgsql-hackers 
On Thu, Apr 14, 2022 at 3:23 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> If we captured equivalent output from the manual VACUUM in test_setup,
> maybe something could be learned.  However, it seems virtually certain
> to me that the problematic xmin is in some background process
> (eg autovac launcher) and thus wouldn't show up in the postmaster log,
> log_line_prefix or no.

A bunch of autovacuums that ran between "2022-04-14 22:49:16.274" and
"2022-04-14 22:49:19.088" all have the same "removable cutoff".

The logs from this time show a period of around three seconds
(likely more) where something held back OldestXmin generally.
That does seem a bit fishy to me, even though it happened about a
minute after the failure itself took place.

--
Peter Geoghegan

Commits

  1. Repurpose PROC_COPYABLE_FLAGS as PROC_XMIN_FLAGS

  2. Tighten ComputeXidHorizons' handling of walsenders.

  3. Adjust VACUUM's removable cutoff log message.

  4. Temporarily add some probes of tenk1's relallvisible in create_index.sql.

  5. Set synchronous_commit=on in test_setup.sql.

  6. Rearrange core regression tests to reduce cross-script dependencies.

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