https://spark-project.atlassian.net/browse/SPARK-1090
spark-shell should print help information about parameters and should allow user to configure exe memory
there is no document about hot to set --cores/-c in spark-shell
and also
users should be able to set executor memory through command line options
In this PR I also check the format of the options passed by the user
Author: CodingCat <zhunansjtu@gmail.com>
Closes#599 from CodingCat/spark_shell_improve and squashes the following commits:
de5aa38 [CodingCat] add parameter to set driver memory
915cbf8 [CodingCat] improvement on spark_shell (help information, configure memory)
e0d49ad229