[zeromq-dev] Logging HWM events?

[Martin Sustrik]

Hi Tom,

> I have an app using PUB/SUB over TCP. Is there a way to log when HWM is
> reached and we have entered into an exceptional state?

There's no in-built mechanism for that.

Also note that there's a separate HWM for each underlying connection, so 
even if you would see "HWM reached" notification it wouln't be clear 
which peer it applies to.

> We had a problem today where it appears that the PUB/SUB link went quiet
> for almost 30 minutes (it is usually processing hundreds or thousands of
> messages per second). Then we saw a slow trickle of very stale (i.e. 30
> minutes old) messages that lasted for another 30 minutes or so before I
> figured out that there was a problem and restarted the client.

Was the delay caused by 0MQ or the application?

In the former case it's a bug and we should try to solve it.

Martin