[zeromq-dev] Using system select with ZMQ Dealer/Router and Multi-Part messages

[Pieter Hintjens]

On Mon, Feb 11, 2013 at 2:45 PM, Tobias Scharnberg
<t.scharnberg at wenzel-elektronik.de> wrote:

> The returned file descriptor is also used internally by the zmq_send and
> zmq_recv functions. As the descriptor is edge triggered, applications
> must update the state of ZMQ_EVENTS after each invocation of zmq_send or
> zmq_recv.

This is a dramatically poor explanation that has tripped up many people.

I've not used this option but from reading the code, this is what it
means: reading the ZMQ_EVENTS socket option has the side-effect of
processing commands internally. So you will have to (afaiu) read that
option after sending/receiving each part.

-Pieter