宽依赖窄依赖
https://blog.csdn.net/houmou/article/details/52531205
hadoop/spark面试
https://blog.csdn.net/qq1010885678/article/details/46916857
spark基本概念
https://blog.csdn.net/u011317245/article/details/52422703
Stage划分
https://blog.csdn.net/sinat_25306771/article/details/51429984