Re: Repeated requests for feedback in logical standby

On Thu, Apr 14, 2016 at 7:34 AM, Nick Cleaton <nick(at)cleaton(dot)net> wrote:

> On 12 April 2016 at 16:18, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> >
> > I've been running some tests, and come across a weird behavior on
> shutdown with logical replication, 9.5.2. It seems that on shutdown, a lot
> of extra requests for feedback are sent from the walsender.
> >
> > On my laptop I get about 3-15 requests (different each time), and on a
> server with a bit more power but still very low activity, the number is
> simply huge.
> >
> > Basically what happens is:
> >
> > * Replication works fine
> > * I have *zero* activity on the master since it got started, not even a
> single psql
> > * I issue a fast shutdown on the master
> > * Nothing happens at all for a while
> > * Once pg_recvlogical times out and sends a status message things wake up
> > * The server sends a whole bunch of requests for status, which
> pg_recvlogical responds to
> > * Eventually things shut down (on the proper server, I've had to kill
> things because it takes too long - I'm unsure if it ever shuts down)
>
>
> That sounds similar to something I've seen with wal-based replication:
>
> http://www.postgresql.org/message-id/flat/CAFgz3kus=rC_avEgBV=+hRK5HYJ8vXskJRh8yEAbahJGTzF2VQ(at)mail(dot)gmail(dot)com#CAFgz3kus=rC_avEgBV=+hRK5HYJ8vXskJRh8yEAbahJGTzF2VQ@mail.gmail.com

Agreed, that sounds very similar.

I don't know the code enough to say whether that's a proper fix though, or
if it might have other sideeffects.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/