Github user colorant commented on the pull request:
https://github.com/apache/incubator-spark/pull/553#issuecomment-34830448
@sryza I think this depends on what you mean to do with the yarn-client
mode, for spark-shell, since it is already packaged in the assembly jar. you
don't need to set the SPARK_YARN_APP_JAR env. And the yarn doc just happen to
take spark-shell as an example. While for those user apps which are not
packaged in the spark assembly jar, you will need it , for either
yarn-standalone and yarn-client mode. ( while, there are also other ways to add
them, say with --files etc, but this one is a shortcut and actually treat
default local file URL format differently ).
