Re: Testing LISTEN/NOTIFY more effectively

I wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
>> Hm. I wonder if all that's happening with prairedog is that the notice
>> is sent a bit later. I think that could e.g. conceivably happen because
>> it TCP_NODELAY isn't supported on prariedog? Or just because the machine
>> is very slow?

> The notices (not notifies) are coming out in the opposite order from
> expected. I haven't really thought hard about what's causing that;
> it seems odd, because isolationtester isn't supposed to give up waiting
> for a session until it's visibly blocked according to pg_locks. Maybe
> it needs to recheck for incoming data once more after seeing that?

Ah-hah, that seems to be the answer. With the attached patch I'm
getting reliable-seeming passes on prairiedog.

regards, tom lane