标签：
http://www.cnblogs.com/Anker/p/3254269.html
http://blog.csdn.net/historyasamirror/article/details/5778378
http://www.smithfox.com/?e=191
IO - 同步，异步，阻塞，非阻塞
原文地址：http://my.oschina.net/u/141132/blog/492112
