[SPARK-4465] runAsSparkUser doesn't affect TaskRunner in Mesos enviro…

…nme...

...nt at all.

- fixed a scope of runAsSparkUser from MesosExecutorDriver.run to MesosExecutorBackend.launchTask
- See the Jira Issue for more details.

Author: Jongyoul Lee <jongyoul@gmail.com>

Closes #3741 from jongyoul/SPARK-4465 and squashes the following commits:

46ad71e [Jongyoul Lee] [SPARK-4465] runAsSparkUser doesn't affect TaskRunner in Mesos environment at all. - Removed unused import
3d6631f [Jongyoul Lee] [SPARK-4465] runAsSparkUser doesn't affect TaskRunner in Mesos environment at all. - Removed comments and adjusted indentations
2343f13 [Jongyoul Lee] [SPARK-4465] runAsSparkUser doesn't affect TaskRunner in Mesos environment at all. - fixed a scope of runAsSparkUser from MesosExecutorDriver.run to MesosExecutorBackend.launchTask

core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala

@@ -22,7 +22,7 @@ import java.nio.ByteBuffer
 import scala.collection.JavaConversions._
 
 import org.apache.mesos.protobuf.ByteString
-import org.apache.mesos.{Executor => MesosExecutor, ExecutorDriver, MesosExecutorDriver, MesosNativeLibrary}
+import org.apache.mesos.{Executor => MesosExecutor, ExecutorDriver, MesosExecutorDriver}
 import org.apache.mesos.Protos.{TaskStatus => MesosTaskStatus, _}
 
 import org.apache.spark.{Logging, TaskState, SparkConf, SparkEnv}
@@ -80,7 +80,9 @@ private[spark] class MesosExecutorBackend
     if (executor == null) {
       logError("Received launchTask but executor was null")
     } else {
-      executor.launchTask(this, taskId, taskInfo.getName, taskInfo.getData.asReadOnlyByteBuffer)
+      SparkHadoopUtil.get.runAsSparkUser { () =>
+        executor.launchTask(this, taskId, taskInfo.getName, taskInfo.getData.asReadOnlyByteBuffer)
+      }
     }
   }
 
@@ -112,11 +114,8 @@ private[spark] class MesosExecutorBackend
 private[spark] object MesosExecutorBackend extends Logging {
   def main(args: Array[String]) {
     SignalLogger.register(log)
-    SparkHadoopUtil.get.runAsSparkUser { () =>
-        MesosNativeLibrary.load()
-        // Create a new Executor and start it running
-        val runner = new MesosExecutorBackend()
-        new MesosExecutorDriver(runner).run()
-    }
+    // Create a new Executor and start it running
+    val runner = new MesosExecutorBackend()
+    new MesosExecutorDriver(runner).run()
   }
 }