hadoop之mapreduce原理

http://www.aboutyun.com/thread-6723-1-1.html

http://www.cnblogs.com/z1987/p/5055565.html

http://blog.csdn.net/lanchunhui/article/details/50893582

https://my.oschina.net/leejun2005/blog/82587

http://www.sohu.com/a/147016674_487514