Horton

Re: Testing LISTEN/NOTIFY more effectively

Peter Geoghegan <pg@bowt.ie>

View thread View on postgr.es
From: Peter Geoghegan <pg@bowt.ie>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-07-27T20:53:35Z
Lists: pgsql-hackers 
On Sat, Jul 27, 2019 at 12:39 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Unfortunately, I just found out that on a slow enough machine
> (prairiedog's host) there *is* some variation in when that test's
> notices come out.  I am unsure whether that's to be expected or
> whether there's something wrong there --- Peter, any thoughts?

I don't know why this happens, but it's worth noting that the plpgsql
function that raises these notices ("blurt_and_lock()") is marked
IMMUTABLE (not sure if you noticed that already). This is a deliberate
misrepresentation which is needed to acquire advisory locks at just
the right points during execution.

If I had to guess, I'd guess that it had something to do with that. I
might be able to come up with a better explanation if I saw the diff.

-- 
Peter Geoghegan

Commits

  1. Improve test coverage for LISTEN/NOTIFY.

  2. Don't drop NOTICE messages in isolation tests.

  3. Fix isolationtester race condition for notices sent before blocking.