When having multiple users sharing the same Spark cluster, it's a good idea to isolate the users - make sure that each users runs under a different Linux account and prevent them from accessing data in jobs submitted by other users. Is it currently possible to do with Spark?
The only thing I found about it online is http://rnowling.github.io/spark/2015/04/07/multiuser-spark-mesos.html, and some older Jira about adding support to YARN. Cheers, Eugene
