Re: Server instrumentation for 8.1 - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Server instrumentation for 8.1
Date
Msg-id 330.1115907863@sss.pgh.pa.us
Whole thread Raw
In response to Re: Server instrumentation for 8.1  (Andrew - Supernews <andrew+nonews@supernews.com>)
Responses Re: Server instrumentation for 8.1  (Robert Treat <xzilla@users.sourceforge.net>)
List pgsql-hackers
Andrew - Supernews <andrew+nonews@supernews.com> writes:
> What currently happens is that backends respond to kill -15 (_NOT_ -9)
> by cleaning up and exiting. This code path is used for implementing the
> stop -mfast option, which means that as it currently exists, the cleanup
> only has to be good enough to let other backends get out of critical
> sections and complete their own rollback-and-exit safely.

Exactly.  In theory it probably works fine to allow one backend to exit
via kill -TERM, but it cannot be claimed that that behavior has been
tested to any significant extent --- "fast" shutdown is not stressing it
in the same way.

I think this is largely a question of someone doing a significant amount
of stress testing: gun live server processes with "kill -TERM" in an
active system, and keep an eye out for resource leaks, held locks, and
so on.  It would be more convincing if the processes getting zapped are
executing a wide variety of SQL, too --- I'd not feel very confident
given only tests of killing, say, pgbench threads.
        regards, tom lane


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