1.select，poll，epoll的区别
简明扼要介绍了接口：
https://www.jianshu.com/p/397449cadc9a
说明了select的流程原理：
https://www.cnblogs.com/Anker/p/3265058.html
说明了epoll：
https://www.cnblogs.com/aspirant/p/9166944.html
[epoll使用详解（精髓）：
https://www.cnblogs.com/fnlingnzb-learner/p/5835573.html
2.服务器架构演化
https://www.zhihu.com/question/20657269/answer/32678620
