SNMP Alarms Release-58

You need to handle getting an empty array here, in particular not drop through to the zmq_recv in that case.  This would happen if the stop method is called while this thread was blocked on the pop call - the stop method calls _req_q->terminate() which will force pop to return immediately with a default constructed object (in this case an empty vector).  As it stands, I think the zmq_recv call will suspend indefinitely because we haven't sent anything.