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Re: conchuela timeouts since 2021-10-09 system upgrade

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Noah Misch <noah@leadboat.com>, Andrey Borodin <x4mmm@yandex-team.ru>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>, Michael Paquier <michael@paquier.xyz>, Peter Geoghegan <pg@bowt.ie>, Andres Freund <andres@anarazel.de>
Date: 2021-10-26T20:45:38Z
Lists: pgsql-bugs 
On Wed, Oct 27, 2021 at 3:29 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> [...] I'd be prepared to believe that prairiedog's
> ancient macOS version has some weird bug preventing kevent() from noticing
> available data ... but (a) surely conchuela wouldn't share such a bug,
> and (b) we've been using kevent() for a couple years now, so how come
> we didn't see this before?

There was this case soon after our kqueue support landed:

https://www.postgresql.org/message-id/CA%2BhUKGLzaR5cV0EmZWoVXJDO_XwZpmpQX_sYwCBRE1qLBEcGPQ%40mail.gmail.com

There are a few discussions on the 'net about the flakiness of both
kevent() and poll() around that vintage of macOS (both were new and
shared infrastructure, separate from select()); for example in libcurl
and libevent talked about this and blocked version ranges.

I don't have any ideas about conchuela.  For the next person who
manages to reproduce this, just to sanity-check what we're passing in
to kevent(), what do *port and waitfor look like when secure_read()
blocks in WaitEventSetWait?  It's good news that Andrey could
reproduce this on a VM.  I may look into setting one of those up too.

Commits

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

  1. Improve contrib/amcheck's tests for CREATE INDEX CONCURRENTLY.

  2. Fix minor memory leaks in pg_dump.

  3. Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.

  4. Fix CREATE INDEX CONCURRENTLY for the newest prepared transactions.

  5. Add -w back to the flags for pg_ctl (re)start in PostgresNode

  6. Fix CREATE INDEX CONCURRENTLY for simultaneous prepared transactions.