深入了解Eventlet

Eventlet
一直在研究openstack的代码，发现eventlet是openstack project中很重要的一个module，因此觉得很有必要把它详细的总结一下，好容易明白一些很magic的功能如何实现的，更加体现了python的简洁。
首先需要明白的是eventlet究竟是什么？
官网是如下描述的：

Eventlet is a concurrent networking library for Python that allows you to change how you run your code, not how you write it.

• It uses epoll or libevent for .
• ensure that the developer uses a blocking style of programming that is similar to threading, but provide the benefits of non-blocking I/O.
• The event dispatch is implicit, which means you can easily use Eventlet from the Python interpreter, or as a small part of a larger application.

Eventlet其实是并发(concurrent)的网络库
Eventlet使用了 epoll或libevent实现了大规模非阻塞IO
使用协程保证开发正能够使用阻塞的开发模式，但是提供了no-blocking IO的效率。


Module Reference

• backdoor – Python interactive interpreter within a running process
• corolocal – Coroutine local storage
• debug – Debugging tools for Eventlet
• db_pool – DBAPI 2 database connection pooling
  • Constructor Arguments
  • DatabaseConnector
• event – Cross-greenthread primitive
• greenpool – Green Thread Pools
• greenthread – Green Thread Implementation
• pools - Generic pools of resources
• queue – Queue class
• semaphore – Semaphore classes
• timeout – Universal Timeouts
• websocket – Websocket Server
• wsgi – WSGI server
  • SSL
  • Non-Standard Extension to Support Post Hooks
• eventlet.green.zmq – ?MQ support
• zmq – The pyzmq ?MQ python bindings