Horton

Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

Jelte Fennema-Nio <postgres@jeltef.nl>

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From: Jelte Fennema-Nio <postgres@jeltef.nl>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Noah Misch <noah@leadboat.com>, Jacob Champion <jacob.champion@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, Denis Laxalde <denis.laxalde@dalibo.com>, vignesh C <vignesh21@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Greg Stark <stark@mit.edu>, "Gregory Stark (as CFM)" <stark.cfm@gmail.com>, Jelte Fennema <Jelte.Fennema@microsoft.com>, Daniel Gustafsson <daniel@yesql.se>, Peter Eisentraut <peter@eisentraut.org>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@lists.postgresql.org, Etsuro Fujita <etsuro.fujita@gmail.com>
Date: 2024-03-28T17:13:56Z
Lists: pgsql-hackers 
On Thu, 28 Mar 2024 at 17:43, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> Hah, you're right, I can reproduce with a smaller timeout, and using SET
> LOCAL works as a fix.  If we're doing that, why not reduce the timeout
> to 1ms?  We don't need to wait extra 9ms ...

I think we don't really want to make the timeout too short. Otherwise
the query might get cancelled before we push any query down to the
FDW. I guess that means that for some slow machines even 10ms is not
enough to make the test do the intended purpose. I'd keep it at 10ms,
which seems long enough for normal systems, while still being pretty
short.

Commits

  1. postgres_fdw: re-issue cancel requests a few times if necessary.

  2. Make postgres_fdw's query_cancel test less flaky.

  3. postgres_fdw: Split out the query_cancel test to its own file

  4. Fix copy-paste mistake in PQcancelCreate

  5. Make libpqsrv_cancel's return const char *, not char *

  6. Stabilize postgres_fdw test

  7. libpq-be-fe-helpers.h: wrap new cancel APIs

  8. dblink/isolationtester/fe_utils: Use new cancel API

  9. Put libpq_pipeline cancel test back

  10. Hopefully make libpq_pipeline's new cancel test more reliable

  11. libpq: Add encrypted and non-blocking query cancellation routines

  12. libpq: Move pg_cancel to fe-cancel.c

  13. Add tests for libpq query cancellation APIs

  14. Add missing connection statuses to docs

  15. libpq: Change some static functions to extern

  16. libpq: Add pqReleaseConnHosts function

  17. libpq: Move cancellation related functions to fe-cancel.c

  18. Make spelling of cancelled/cancellation consistent

  19. Be more wary about OpenSSL not setting errno on error.

  20. libpq: Use modern socket flags, if available.

  21. Drop test view when done with it.

  22. Doc: add some doco about using the libpq_pipeline test module.

  23. postgres_fdw: Allow cancellation of transaction control commands.