Re: pgsql: Add support for temporary replication slots

On 2016-12-12 20:08:01 -0500, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2016-12-13 01:57:01 +0100, Petr Jelinek wrote:
> >> I mentioned that as possible solution upthread, I am only worried that
> >> the failure scenario is basically infinite loop.
>
> > I don't see the problem with that. If you're really concerned you can
> > set a statement timeout.
>
> I don't think "change the test" is the right response here.
> I think the problem is that we're disconnecting from the slot at the
> wrong step of backend shutdown, and that we need to fix that before
> it bites us on some more painful parts of our anatomies. You can't
> just throw darts at the code when deciding where to do things, and
> proc.c is NOT the place that should be concerned with replication
> slots.

And why is that / where would be more appropriate? It's not
ShutdownPostgres() (usable from bgworkers). And it has to be
after LWLockReleaseAll(), because otherwise we'll potentially just
deadlock against ourselves.

Greetings,

Andres Freund