Recovering from zmq.error.ZMQError: Address already in use

Question

I hit Ctrl-C while running a PAIR pattern (non-blocking client servers) connection with ZMQ. Later when I tried running the REQ-REP (blocking client single server connection) pattern, I keep getting the Address already in use error. I have tried running netstat with netstat -ltnp | grep :<my port> but that does not list any process.

So who exactly is using this address?

Also how does one gracefully shutdown socket connections like these?

Answer 1

Question 1:

If you do sudo netstat -ltnp, on a Linux type operating system, you will most probably see the process owning the port. Kill it with kill -9 <pid>.

Question 2:

When you exit the program, close your sockets and then call zmq_ctx_destroy(). This destroys the context. See http://zguide.zeromq.org/page:all#toc17 for more info.

Answer 2

At this very moment:

reboot 

Next:

start using try: / except: / finally: encapsulation constructors, that will help you to grant a graceful exit from all zmq allocations, incl. all Socket-s' .close() and Context's .term() without any hanging orphan(s) an memory leak(s), even in case any panic button or unhandled exception interrupts your code-execution altogether with losing references to your still hanging, network-hardware bound, instances.