Обсуждение: pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.

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pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.

От
Thomas Munro
Дата:
Add WL_EXIT_ON_PM_DEATH pseudo-event.

Users of the WaitEventSet and WaitLatch() APIs can now choose between
asking for WL_POSTMASTER_DEATH and then handling it explicitly, or asking
for WL_EXIT_ON_PM_DEATH to trigger immediate exit on postmaster death.
This reduces code duplication, since almost all callers want the latter.

Repair all code that was previously ignoring postmaster death completely,
or requesting the event but ignoring it, or requesting the event but then
doing an unconditional PostmasterIsAlive() call every time through its
event loop (which is an expensive syscall on platforms for which we don't
have USE_POSTMASTER_DEATH_SIGNAL support).

Assert that callers of WaitLatchXXX() under the postmaster remember to
ask for either WL_POSTMASTER_DEATH or WL_EXIT_ON_PM_DEATH, to prevent
future bugs.

The only process that doesn't handle postmaster death is syslogger.  It
waits until all backends holding the write end of the syslog pipe
(including the postmaster) have closed it by exiting, to be sure to
capture any parting messages.  By using the WaitEventSet API directly
it avoids the new assertion, and as a by-product it may be slightly
more efficient on platforms that have epoll().

Author: Thomas Munro
Reviewed-by: Kyotaro Horiguchi, Heikki Linnakangas, Tom Lane
Discussion: https://postgr.es/m/CAEepm%3D1TCviRykkUb69ppWLr_V697rzd1j3eZsRMmbXvETfqbQ%40mail.gmail.com,
            https://postgr.es/m/CAEepm=2LqHzizbe7muD7-2yHUbTOoF7Q+qkSD5Q41kuhttRTwA@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/cfdf4dc4fc9635ac8bf6eaaa5dbbcd364ab29f0c

Modified Files
--------------
-                                                  |  0
contrib/pg_prewarm/autoprewarm.c                   |  8 ++--
contrib/postgres_fdw/connection.c                  |  6 ++-
src/backend/access/transam/parallel.c              | 10 ++---
src/backend/access/transam/xlog.c                  | 23 +++++-----
src/backend/access/transam/xlogfuncs.c             |  8 ++--
src/backend/executor/nodeGather.c                  |  3 +-
src/backend/libpq/be-secure-openssl.c              |  4 +-
src/backend/libpq/pqmq.c                           |  4 +-
src/backend/postmaster/autovacuum.c                | 16 ++-----
src/backend/postmaster/bgwriter.c                  | 11 +----
src/backend/postmaster/checkpointer.c              | 16 ++-----
src/backend/postmaster/pgarch.c                    |  4 +-
src/backend/postmaster/syslogger.c                 | 38 ++++++++++-------
src/backend/postmaster/walwriter.c                 | 16 ++-----
src/backend/replication/basebackup.c               |  2 +-
.../libpqwalreceiver/libpqwalreceiver.c            | 13 +-----
src/backend/replication/logical/launcher.c         | 24 ++---------
src/backend/replication/logical/tablesync.c        | 30 ++++---------
src/backend/replication/logical/worker.c           |  6 +--
src/backend/replication/syncrep.c                  | 18 ++++----
src/backend/replication/walreceiver.c              | 22 ++--------
src/backend/replication/walsender.c                | 49 +++++++---------------
src/backend/storage/ipc/latch.c                    | 38 ++++++++++++++++-
src/backend/storage/ipc/shm_mq.c                   |  9 ++--
src/backend/storage/lmgr/condition_variable.c      | 14 ++-----
src/backend/storage/lmgr/proc.c                    |  7 ++--
src/backend/utils/adt/misc.c                       |  2 +-
src/include/storage/latch.h                        |  3 +-
src/test/modules/test_shm_mq/setup.c               |  3 +-
src/test/modules/test_shm_mq/test.c                |  3 +-
src/test/modules/worker_spi/worker_spi.c           |  6 +--
32 files changed, 174 insertions(+), 242 deletions(-)


Re: pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.

От
Tom Lane
Дата:
Thomas Munro <tmunro@postgresql.org> writes:
> Add WL_EXIT_ON_PM_DEATH pseudo-event.

This patch added an empty file at the top of the git tree:

> Modified Files
> --------------
> -                                                  |  0

I assume this was a mistake.  Please be more careful in future.

            regards, tom lane


Re: pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.

От
Thomas Munro
Дата:
On Sat, Nov 24, 2018 at 4:20 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Thomas Munro <tmunro@postgresql.org> writes:
> > -                                                  |  0
>
> I assume this was a mistake.  Please be more careful in future.

Sorry, somehow this cruft was hiding in plain sight in the last couple
of patch revisions I posted.  Thanks for removing it.

-- 
Thomas Munro
http://www.enterprisedb.com


Re: pgsql: Add WL_EXIT_ON_PM_DEATH pseudo-event.

От
Michael Paquier
Дата:
On Fri, Nov 23, 2018 at 07:54:42AM +0000, Thomas Munro wrote:
> Add WL_EXIT_ON_PM_DEATH pseudo-event.

I was not paying much attention to this thread, but that's a nice
cleanup.  Thanks, Thomas.

[... switching stuff to the new option ...]
--
Michael

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