Horton

Re: On login trigger: take three

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mikhail Gribkov <youzhick@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>, Michael Paquier <michael@paquier.xyz>, Robert Haas <robertmhaas@gmail.com>, Daniel Gustafsson <daniel@yesql.se>, Andres Freund <andres@anarazel.de>, Greg Nancarrow <gregn4422@gmail.com>, Ivan Panchenko <wao@mail.ru>, Teodor Sigaev <teodor@sigaev.ru>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, vignesh C <vignesh21@gmail.com>, Pavel Stehule <pavel.stehule@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2023-10-29T15:16:01Z
Lists: pgsql-hackers 
Mikhail Gribkov <youzhick@gmail.com> writes:
> Just for a more complete picture of the final state here.
> I have posted the described fix (for avoiding race condition in the tests)
> separately:
> https://commitfest.postgresql.org/45/4616/

It turns out that the TAP test for this feature (006_login_trigger.pl)
also has a race condition:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mamba&dt=2023-10-28%2003%3A33%3A28

The critical bit of the log is

ack Broken pipe: write( 14, 'SELECT 1;' ) at /usr/pkg/lib/perl5/vendor_perl/5.36.0/IPC/Run/IO.pm line 550.

It looks to me that what happened here is that the backend completed the
authentication handshake, and then the login trigger caused a FATAL exit,
and after than the connected psql session tried to send "SELECT 1" on
an already-closed pipe.  That failed, causing IPC::Run to panic.

mamba is a fairly slow machine and doubtless has timing a bit different
from what this test was created on.  But I doubt there is any way to make
this behavior perfectly stable across a range of machines, so I recommend
just removing the test case involving a fatal exit.

			regards, tom lane

Commits

  1. Fix some typos in event trigger docs

  2. Use heap_inplace_update() to unset pg_database.dathasloginevt

  3. Remove the flaky check in event_trigger_login regression test

  4. Fix instable 006_login_trigger.pl test

  5. Add support event triggers on authenticated login

  6. Add GUC for temporarily disabling event triggers

  7. Fix typo in reference to __FreeBSD__.

  8. Restore robustness of TAP tests that wait for postmaster restart.

  9. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.