MAPREDUCE-6492. AsyncDispatcher exit with NPE on TaskAttemptImpl#sendJHStartEventForAssignedFailTask. Contributed by Bibin A Chundatt

(cherry picked from commit ab11085b81353e1617875deb10f3c8e2a8b91a1e)
(cherry picked from commit fc10c9983901cd231f8ec959675d741512716b9e)

Conflicts:

	hadoop-mapreduce-project/CHANGES.txt

hadoop-mapreduce-project/CHANGES.txt

@@ -13,6 +13,10 @@ Release 2.6.4 - UNRELEASED
     MAPREDUCE-5982. Task attempts that fail from the ASSIGNED state can
     disappear (Chang Li via jlowe)
 
+    MAPREDUCE-6492. AsyncDispatcher exit with NPE on
+    TaskAttemptImpl#sendJHStartEventForAssignedFailTask (Bibin A Chundatt via
+    jlowe)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/TaskAttemptImpl.java

@@ -1374,7 +1374,9 @@ public abstract class TaskAttemptImpl implements
 
   private static void
       sendJHStartEventForAssignedFailTask(TaskAttemptImpl taskAttempt) {
-    TaskAttemptContainerLaunchedEvent event;
+    if (null == taskAttempt.container) {
+      return;
+    }
     taskAttempt.launchTime = taskAttempt.clock.getTime();
 
     InetSocketAddress nodeHttpInetAddr =

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/job/impl/TestTaskAttempt.java

@@ -753,6 +753,14 @@ public class TestTaskAttempt{
     assertFalse(
         "InternalError occurred trying to handle TA_DIAGNOSTICS_UPDATE on assigned task",
         eventHandler.internalError);
+    try {
+      taImpl.handle(new TaskAttemptEvent(attemptId,
+          TaskAttemptEventType.TA_KILL));
+      Assert.assertTrue("No exception on UNASSIGNED STATE KILL event", true);
+    } catch (Exception e) {
+      Assert.assertFalse(
+          "Exception not expected for UNASSIGNED STATE KILL event", true);
+    }
   }
 
   @Test