Re: Race conditions with WAL sender PID lookups

On Thu, May 11, 2017 at 10:48 AM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> Hi all,
>
> I had my eyes on the WAL sender code this morning, and I have noticed
> that walsender.c is not completely consistent with the PID lookups it
> does in walsender.c. In two code paths, the PID value is checked
> without holding the WAL sender spin lock (WalSndRqstFileReload and
> pg_stat_get_wal_senders), which looks like a very bad idea contrary to
> what the new WalSndWaitStopping() does and what InitWalSenderSlot() is
> doing for ages.
>
> Any thoughts about the patch attached to make things more consistent?
> It seems to me that having some safeguards would be nice for
> robustness.

+1. I think this is a sensible change.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center