Horton

Re: [sqlsmith] stuck spinlock in pg_stat_get_wal_receiver after OOM

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Andreas Seltenreich <seltenreich@gmx.de>, pgsql-hackers@postgresql.org, Alvaro Herrera <alvherre@2ndquadrant.com>, Michael Paquier <michael.paquier@gmail.com>
Date: 2017-10-02T21:30:25Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2017-10-02 22:56:49 +0200, Andreas Seltenreich wrote:
>> low-memory testing with REL_10_STABLE at 1f19550a87 produced the
>> following PANIC:
>> stuck spinlock detected at pg_stat_get_wal_receiver, walreceiver.c:1397

> Ugh.

Egad.

> Yes, that'd be a bad idea. It's not great to have memcpys in a critical
> section, but it's way better than pallocs. So we need to use some local
> buffers that this get copied to.

Or replace the spinlock with an LWLock?  In any case, I think it would be
a good idea to look at every other critical section touching that lock
to see if there are any other blatant coding-rule violations.

			regards, tom lane

Commits

  1. Fix race condition with unprotected use of a latch pointer variable.

  2. Fix coding rules violations in walreceiver.c

  3. Use latch instead of select() in walreceiver