gevent, gunicorn 文档及博客资料
https://sdiehl.github.io/gevent-tutorial/
https://www.zybuluo.com/orangleliu/note/302677
http://gunicorn.readthedocs.io/en/latest/index.html
https://words.volant.is/articles/understanding-gunicorns-async-worker-concurrency-model/
https://words.volant.is/articles/understanding-gunicorns-async-worker-concurrency-model/
http://docs.gunicorn.org/en/stable/design.html
http://www.shuaiyy.cn/2017/11/05/%E6%8A%80%E6%9C%AF/Gevent%20%E6%BA%90%E7%A0%81%E5%88%86%E6%9E%90/
http://blog.rootk.com/post/Gevent%E7%9A%84hub%E5%89%96%E6%9E%90.html
https://yuyang0.github.io/articles/gevent.html
tornado ioloop
http://rur.logdown.com/posts/2015/03/06/tornado-source-ioloop