Merge r1594795 from trunk: MAPREDUCE-5861. finishedSubMaps field in LocalContainerLauncher does not need to be volatile. (Contributed by Tsuyoshi OZAWA)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1594797 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -55,6 +55,9 @@ Release 2.5.0 - UNRELEASED
     MAPREDUCE-5652. NM Recovery. ShuffleHandler should handle NM restarts.
     (Jason Lowe via kasha)
 
+    MAPREDUCE-5861. finishedSubMaps field in LocalContainerLauncher does not 
+    need to be volatile. (Tsuyoshi OZAWA via junping_du)
+
   OPTIMIZATIONS
 
   BUG FIXES 

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapred/LocalContainerLauncher.java

@@ -177,8 +177,10 @@ public class LocalContainerLauncher extends AbstractService implements
    */
   private class EventHandler implements Runnable {
 
-    private volatile boolean doneWithMaps = false;
-    private volatile int finishedSubMaps = 0;
+    // doneWithMaps and finishedSubMaps are accessed from only
+    // one thread. Therefore, no need to make them volatile.
+    private boolean doneWithMaps = false;
+    private int finishedSubMaps = 0;
 
     private final Map<TaskAttemptId,Future<?>> futures =
         new ConcurrentHashMap<TaskAttemptId,Future<?>>();