[zeromq-dev] epgm debugging help

[Pieter Hintjens]

Hi Tom,

Some essential data you do need to provide:

- what version of 0MQ
- what OS and version
- test case, if possible

Thanks
Pieter

On Wed, Apr 27, 2011 at 7:13 PM, Tom Wilberding <tom at wilberding.com> wrote:
> Hi All,
>
> We have a simple application that consumes PUB/SUB messages via TCP
> (over an expensive WAN link) and fans them out PUB/SUB via epgm on.the
> local LAN.
>
> We have an client that is SUBing to the epgm messages and things seem to
> work fine for long stretches of time. This client is intended to stay
> connected 24x7 and data flows nearly constantly at all times.
>
> But occasionally the client stops processing data and debugging our code
> suggests that calls to zmq_poll() are not returning data.
>
> I did a tcpdump on the epgm PUB side and also on the epgm SUB side. In
> both cases, data continues to flow from PUB to SUB (from the NIC's
> perspective) even after the client stops processing data. I ran a
> netstat -g after the failure and the IGMP subscription was still active.
> I also did a tcpdump on the IGMP traffic and I continue to see my
> subscriber reporting "V2 Membership Report / Join group".
>
> Any suggestions on how to diagnose this further? Especially any tips for
> being able to log or inspect state within the ZMQ layer? Is there known
> behavior that would explain why ZMQ might "give up" and stop delivering
> to an epgm/SUB client.
>
> I don't have an easy to reproduce case. Rather it happens randomly 2-3
> times per day.
>
> Thanks,
> Tom
>
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
>