Re: LISTEN / NOTIFY performance in 8.3

Joel Stevenson <joelstevenson(at)mac(dot)com> writes:
>> This sounds a bit like pg_listener has gotten bloated. Try a "VACUUM
>> VERBOSE pg_listener" (as superuser) and see what it says.

> At the moment (server is inactive):

> pcdb=# VACUUM VERBOSE pg_listener;
> INFO: vacuuming "pg_catalog.pg_listener"
> INFO: "pg_listener": removed 1 row versions in 1 pages
> INFO: "pg_listener": found 1 removable, 21 nonremovable row versions
> in 28 pages

OK, that destroys the table-bloat theory. Just to make sure, I
pre-populated pg_listener with enough dead rows to make 28 pages,
but I still don't see any slow notifies or noticeable load in vmstat.

That server is not quite "inactive", though. What are the 21 remaining
pg_listener entries for? Is it possible that those jobs are having
some impact on the ones run by the test script?

Also, it might be worth enabling log_lock_waits to see if the slow
notifies are due to having to wait on some lock or other.

regards, tom lane