MAPREDUCE-5744. Job hangs because RMContainerAllocator.preemptReduce() violates the comparator contract (Gera Shegalov via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.3@1565482 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -71,6 +71,10 @@ Release 2.3.0 - UNRELEASED
     MAPREDUCE-5725. Make explicit that TestNetworkedJob relies on the Capacity
     Scheduler (Sandy Ryza)
 
+    MAPREDUCE-5744. Job hangs because 
+    RMContainerAllocator$AssignedRequests.preemptReduce() violates the 
+    comparator contract (Gera Shegalov via kasha)
+
   OPTIMIZATIONS
 
     MAPREDUCE-4680. Job history cleaner should only check timestamps of files in

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java

@@ -1123,9 +1123,9 @@ public class RMContainerAllocator extends RMContainerRequestor
           new Comparator<TaskAttemptId>() {
         @Override
         public int compare(TaskAttemptId o1, TaskAttemptId o2) {
-          float p = getJob().getTask(o1.getTaskId()).getAttempt(o1).getProgress() -
-              getJob().getTask(o2.getTaskId()).getAttempt(o2).getProgress();
-          return p >= 0 ? 1 : -1;
+          return Float.compare(
+              getJob().getTask(o1.getTaskId()).getAttempt(o1).getProgress(),
+              getJob().getTask(o2.getTaskId()).getAttempt(o2).getProgress());
         }
       });