From c0a903da22c65294b232c7530a6a684ee93daba4 Mon Sep 17 00:00:00 2001
From: Michael Stack <stack@apache.org>
Date: Tue, 4 Mar 2014 21:07:03 +0000
Subject: [PATCH] HDFS-6047 TestPread NPE inside in DFSInputStream
 hedgedFetchBlockByteRange (stack)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1574205 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt                | 3 +++
 .../main/java/org/apache/hadoop/hdfs/DFSInputStream.java   | 7 +++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 7908b9ece2..acd5f15ae8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -525,6 +525,9 @@ Release 2.4.0 - UNRELEASED
     HDFS-6040. fix DFSClient issue without libhadoop.so and some other
     ShortCircuitShm cleanups (cmccabe)
 
+    HDFS-6047 TestPread NPE inside in DFSInputStream hedgedFetchBlockByteRange
+    (stack)
+
   BREAKDOWN OF HDFS-5698 SUBTASKS AND RELATED JIRAS
 
     HDFS-5717. Save FSImage header in protobuf. (Haohui Mai via jing9)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
index 5badb24b0a..3705a2fd4f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
@@ -1177,8 +1177,11 @@ private void hedgedFetchBlockByteRange(LocatedBlock block, long start,
           // exception already handled in the call method. getFirstToComplete
           // will remove the failing future from the list. nothing more to do.
         }
-        // We got here if exception.  Ignore this node on next go around.
-        ignored.add(chosenNode.info);
+        // We got here if exception.  Ignore this node on next go around IFF
+        // we found a chosenNode to hedge read against.
+        if (chosenNode != null && chosenNode.info != null) {
+          ignored.add(chosenNode.info);
+        }
       }
       // executed if we get an error from a data node
       block = getBlockAt(block.getStartOffset(), false);