[SPARK-9969] [YARN] Remove old MR classpath API support

Here propose to remove old MRJobConfig#DEFAULT_APPLICATION_CLASSPATH support, since we now move to Yarn stable API.

vanzin and sryza , any opinion on this? If we still want to support old API, I can close it. But as far as I know now major Hadoop releases has moved to stable API.

Author: jerryshao <sshao@hortonworks.com>

Closes #8192 from jerryshao/SPARK-9969.

1 files changed, 1 insertions, 11 deletions

diff --git a/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala b/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
index 5c6a716863..8672ef6017 100644
--- a/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
+++ b/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
@@ -1098,20 +1098,10 @@ object Client extends Logging {
     triedDefault.toOption
   }
 
-  /**
-   * In Hadoop 0.23, the MR application classpath comes with the YARN application
-   * classpath. In Hadoop 2.0, it's an array of Strings, and in 2.2+ it's a String.
-   * So we need to use reflection to retrieve it.
-   */
   private[yarn] def getDefaultMRApplicationClasspath: Option[Seq[String]] = {
     val triedDefault = Try[Seq[String]] {
       val field = classOf[MRJobConfig].getField("DEFAULT_MAPREDUCE_APPLICATION_CLASSPATH")
-      val value = if (field.getType == classOf[String]) {
-        StringUtils.getStrings(field.get(null).asInstanceOf[String]).toArray
-      } else {
-        field.get(null).asInstanceOf[Array[String]]
-      }
-      value.toSeq
+      StringUtils.getStrings(field.get(null).asInstanceOf[String]).toSeq
     } recoverWith {
       case e: NoSuchFieldException => Success(Seq.empty[String])
     }