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: Denis Laxalde <denis.laxalde@dalibo.com>, vignesh C <vignesh21@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Greg Stark <stark@mit.edu>, Tom Lane <tgl@sss.pgh.pa.us>, "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" <pgsql-hackers@lists.postgresql.org>
Date: 2024-03-12T22:43:03Z
Lists: pgsql-hackers 
On Tue, 12 Mar 2024 at 19:28, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2024-Mar-12, Alvaro Herrera wrote:
>
> > Hmm, buildfarm member kestrel (which uses
> > -fsanitize=undefined,alignment) failed:
> >
> > # Running: libpq_pipeline -r 700 cancel port=49975 host=/tmp/dFh46H7YGc
> > dbname='postgres'
> > test cancellations...
> > libpq_pipeline:260: query did not fail when it was expected
>
> Hm, I tried using the same compile flags, couldn't reproduce.

Okay, it passed now it seems so I guess this test is flaky somehow.
The error message and the timing difference between failed and
succeeded buildfarm run clearly indicates that the pg_sleep ran its
180 seconds to completion (so cancel was never processed for some
reason).

**failed case**
282/285 postgresql:libpq_pipeline / libpq_pipeline/001_libpq_pipeline
           ERROR           191.56s   exit status 1

**succeeded case**

252/285 postgresql:libpq_pipeline / libpq_pipeline/001_libpq_pipeline
           OK               10.01s   21 subtests passed

I don't see any obvious reason for how this test can be flaky, but
I'll think a bit more about it tomorrow.

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.