[GitHub] incubator-spark pull request: Adding an option to persist Spark RD...

[RongGu]

Github user RongGu commented on the pull request:

    https://github.com/apache/incubator-spark/pull/468#discussion_r9762266
  
    Actually, the compiler would report [error] (Note that variables need to be 
initialized to be defined) here. So, I initialize it with null.