参考：
https://www.cnblogs.com/silence-cho/p/12657234.html
https://learning-0mq-with-pyzmq.readthedocs.io/en/latest/pyzmq/patterns/pushpull.html
https://segmentfault.com/a/1190000012010573
ZeroMQ：基于socket，跨进程、跨ip通信。
ZeroMQ的三种通信模式分别是：Request-Reply， Publisher-subscriber, Parallel Pipeline
python安装zmq模块：pip install pyzmq