The way I solved this problem was to call asys.shutdown() on exit. I do this by capturing KeyboardInterrupt and calling asys.shutdown(). A try finally might also work. I don't recommend the time.sleep but I am still trying to wrap my head around this.
asys = ActorSystem("multiprocTCPBase")
try:
asys.createActor(Server, globalName="Server")
while True:
time.sleep(0.2)
except KeyboardInterrupt:
asys.shutdown()