整理

https://blog.csdn.net/qq_32023541/article/details/79282179    关于RDD和DataFrame 的缓存

http://ifeve.com/spark-sql-dataframes/

https://www.cnblogs.com/tgzhu/p/5822370.html               Spark内存

https://www.zhihu.com/question/41922036/answer/93079526       GC