Hadoop之MapReduce

MapReduce基本概念及工作过程：

http://www.cnblogs.com/edisonchou/p/4287784.html

Shuffler过程

http://langyu.iteye.com/blog/992916

数据倾斜与shuffle类性能调优

http://blog.youkuaiyun.com/pengych_321/article/details/52260361