Re: Race conditions with WAL sender PID lookups

On Wed, May 17, 2017 at 12:14 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Well, it's probably worth changing for consistency, but I'm not sure
> that it rises to the level of "a very bad idea". It actually seems
> almost entirely harmless. Spuriously setting the needreload flag on a
> just-deceased WAL sender will just result in some future WAL sender
> doing a bit of unnecessary work, but I don't think it breaks anything
> and the probability is vanishingly low. The other change could result
> a bogus 0 PID in pg_stat_get_wal_senders output, but I bet you
> couldn't reproduce that more than once in a blue moon even with a test
> rig designed to provoke it, and if it does happen it isn't really
> anything more than a trivial annoyance.

Well, the window is very low, so only tests with precisely taken
breakpoints would show problems.

> So I'm in favor of committing this and maybe even back-patching it,
> but I also don't think it's a big deal.

Thanks. I would not mind if this is seen as a HEAD-only improvement.
--
Michael