From 386e62ace38502399500aabf70325892eb179ee5 Mon Sep 17 00:00:00 2001
From: Jason Lowe <jlowe@apache.org>
Date: Wed, 18 Feb 2015 19:28:02 +0000
Subject: [PATCH] MAPREDUCE-6261. NullPointerException if MapOutputBuffer.flush
 invoked twice. Contributed by Tsuyoshi OZAWA (cherry picked from commit
 4981d082d4f3c82d1c2c900c7488b83bf20301cc)

---
 hadoop-mapreduce-project/CHANGES.txt                          | 3 +++
 .../src/main/java/org/apache/hadoop/mapred/MapTask.java       | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 1332cd76a58..79c14ca7dcd 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -137,6 +137,9 @@ Release 2.7.0 - UNRELEASED
     MAPREDUCE-4286. TestClientProtocolProviderImpls passes on failure 
     conditions. (Devaraj K via ozawa)
 
+    MAPREDUCE-6261. NullPointerException if MapOutputBuffer.flush invoked
+    twice (Tsuyoshi OZAWA via jlowe)
+
 Release 2.6.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
index 1a4901b257d..80943178298 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
@@ -1458,6 +1458,10 @@ public class MapTask extends Task {
     public void flush() throws IOException, ClassNotFoundException,
            InterruptedException {
       LOG.info("Starting flush of map output");
+      if (kvbuffer == null) {
+        LOG.info("kvbuffer is null. Skipping flush.");
+        return;
+      }
       spillLock.lock();
       try {
         while (spillInProgress) {