Horton

Re: [sqlsmith] stuck spinlock in pg_stat_get_wal_receiver after OOM

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Andreas Seltenreich <seltenreich@gmx.de>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-10-02T21:05:16Z
Lists: pgsql-hackers 
On Tue, Oct 3, 2017 at 9:56 AM, Andreas Seltenreich <seltenreich@gmx.de> 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
>
> I was about to wrap the pstrdup()s with a PG_TRY block, but I can't find
> a spinlock being released in a PG_CATCH block anywhere, so maybe that's
> a bad idea?

No comment on what might be holding the spinlock there, but perhaps
the spinlock-protected code should strncpy into stack-local buffers
instead of calling pstrdup()?  The buffers could be statically sized
with NAMEDATALEN and MAXCONNINFO.

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

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