Re: Monitoring and insight into NOTIFY queue

On 02/19/2016 06:01 AM, Jiří Hlinka wrote:
> Hello,
>
> I'd like to ask you whether there is a way how to monitor and log
> details about NOTIFY queue? What do you use for this prupose?
>
> In the official documentation I'm unable to find a way how to monitor
> NOTIFY queue in more detail, at least size of this queue, which is
> critical in case of filling up the queue, which will lead to stopping
> the NOTIFY queue functionality.

Should have added from:

http://www.postgresql.org/docs/9.5/interactive/sql-notify.html

"Once the queue is half full you will see warnings in the log file
pointing you to the session that is preventing cleanup. In this case you
should make sure that this session ends its current transaction so that
cleanup can proceed"

Where the message is of form(from async.c):

(errmsg("NOTIFY queue is %.0f%% full", fillDegree * 100),
(minPid != InvalidPid ?
errdetail("The server process with
PID %d is among those with the oldest transactions.", minPid)
: 0),
(minPid != InvalidPid ?
errhint("The NOTIFY queue cannot be
emptied until that process ends its current transaction.")
: 0)));

>
> Thanks,
> Jiri

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com