From b838ac89a673c465d96b71c9c5eae8e4e26b8608 Mon Sep 17 00:00:00 2001
From: Suresh Srinivas <suresh@apache.org>
Date: Tue, 24 Sep 2013 05:31:02 +0000
Subject: [PATCH] HDFS-5251. Race between the initialization of NameNode and
 the http server. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1525787 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt        |  3 +++
 .../hdfs/server/namenode/NamenodeJspHelper.java    |  4 ++++
 .../server/namenode/TestNameNodeJspHelper.java     | 14 ++++++++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index ac3bc726061..25db6583df4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -327,6 +327,9 @@ Release 2.2.0 - UNRELEASED
 
     HDFS-5139. Remove redundant -R option from setrep.
 
+    HDFS-5251. Race between the initialization of NameNode and the http
+    server. (Haohui Mai via suresh)
+
 Release 2.1.1-beta - 2013-09-23
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeJspHelper.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeJspHelper.java
index e2aa4fcf7c5..022c7ba0eae 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeJspHelper.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeJspHelper.java
@@ -101,6 +101,10 @@ class NamenodeJspHelper {
   }
 
   static String getRollingUpgradeText(FSNamesystem fsn) {
+    if (fsn == null) {
+      return "";
+    }
+
     DatanodeManager dm = fsn.getBlockManager().getDatanodeManager();
     Map<String, Integer> list = dm.getDatanodesSoftwareVersions();
     if(list.size() > 1) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeJspHelper.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeJspHelper.java
index 8119d662a6f..a847a9438a3 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeJspHelper.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeJspHelper.java
@@ -18,8 +18,13 @@
 package org.apache.hadoop.hdfs.server.namenode;
 
 
-import static org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase.*;
-import static org.mockito.Mockito.*;
+import static org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase.LOADING_EDITS;
+import static org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase.LOADING_FSIMAGE;
+import static org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase.SAFEMODE;
+import static org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase.SAVING_CHECKPOINT;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
 
 import java.io.IOException;
 import java.util.List;
@@ -107,6 +112,11 @@ public class TestNameNodeJspHelper {
     Assert.assertTrue(containsMatch(contents, SAFEMODE.getDescription()));
   }
 
+  @Test
+  public void testGetRollingUpgradeText() {
+    Assert.assertEquals("", NamenodeJspHelper.getRollingUpgradeText(null));
+  }
+
   /**
    * Checks if the list contains any string that partially matches the regex.
    *