1、HTTP Keep-Alive模式:http://www.cnblogs.com/skynet/archive/2010/12/11/1903347.html
2、浏览器的并发请求限制:http://www.zhihu.com/question/20474326
3、RFC文档 connection部分:http://tools.ietf.org/html/rfc2616#page-44
4、C/C++网络编程中的TCP保活: http://blog.csdn.net/weiwangchao_/article/details/7225338
5、HTTP persistent connection: http://en.wikipedia.org/wiki/HTTP_persistent_connection
6、HTTP pipelining:http://en.wikipedia.org/wiki/HTTP_pipelining
7、Head-of-line blocking:http://en.wikipedia.org/wiki/Head-of-line_blocking
8、《HTTP权威指南》第四章 连接管理