[zeromq-dev] Multi-part message reception over EPGM

[Jim Hague]

Hi,

I'm using PUB-SUB multicasting with EPGM. I'm using subscription topics, so 
sending multi-part messages with the topic in the first part and the content in 
the second part.

In the receiver, I'm doing a zmq_poll(), and if the SUB socket shows data 
waiting I'm then calling zmg_msg_recv() twice, the first time to get the topic 
and the second time the content.

And it's all working well.

But this morning, doing some testing of resilience in the face of network 
problems - in this case disconnect and reconnect of the network lead - I found 
that my receiver program had blocked. Checking with the debugger, I found it 
stuck in the second read. The first read had returned data that was not a 
topic, but a message content, and the second read was blocking, waiting for 
data that wasn't coming.

Am I right in thinking this shouldn't happen? That if poll() says a message is 
waiting, it should be both parts of the multi-part and that there should be no 
way a read of the topic should get content?

Both systems are Debian Sid, libzmq3, 4.0.5+dfsg-3
-- 
Jim Hague - jim.hague at acm.org          Never trust a computer you can't lift.