Celery支持不同的并发和序列化的手段
并发：Prefork, Eventlet, gevent, threads/single threaded
序列化：pickle, json, yaml, msgpack. zlib, bzip2 compression， Cryptographic message signing 等等
默认是进程池方式，进程数以当前机器的CPU核数为参考，每个CPU开四个进程。
如何自己指定进程数： celery worker -A proj --concurrency=4
如何改变进程池方式为协程方式： celery worker -A proj --concurrency=1000 -P eventlet -c 1000
# 安装eventlet模块
$ pip install eventlet
# 启用 Eventlet 池
$ celery -A celery_tasks.main worker -l info -P eventlet -c 1000
https://www.cnblogs.com/yuanfang0903/p/13518236.html
https://docs.celeryproject.org/en/v4.4.6/reference/celery.bin.worker.html#cmdoption-celery-worker-c
https://docs.celeryproject.org/en/v4.4.6/userguide/concurrency/eventlet.html#concurrency-eventlet
