From d082b122f9bdd5d75174242ff4fd65242959696a Mon Sep 17 00:00:00 2001
From: Karthik Kambatla <kasha@apache.org>
Date: Thu, 6 Feb 2014 23:31:04 +0000
Subject: [PATCH] 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@1565479 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-mapreduce-project/CHANGES.txt                        | 4 ++++
 .../hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java    | 6 +++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index a82bb36ded7..59804e95a66 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -91,6 +91,10 @@ 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
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java
index 3c52dcdc00b..17cd19a2210 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/rm/RMContainerAllocator.java
+++ b/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());
         }
       });