From 30569d930f92c4f01c0c6c523c84ef1a9993bead Mon Sep 17 00:00:00 2001
From: Jian He <jianhe@apache.org>
Date: Mon, 14 Sep 2015 17:48:31 +0800
Subject: [PATCH] YARN-4153. TestAsyncDispatcher failed at branch-2.7.
 Contributed by Zhihai Xu

---
 .../java/org/apache/hadoop/util/JvmPauseMonitor.java | 12 +++++++-----
 hadoop-yarn-project/CHANGES.txt                      |  2 ++
 .../apache/hadoop/yarn/event/AsyncDispatcher.java    |  7 +++++--
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/JvmPauseMonitor.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/JvmPauseMonitor.java
index 1fe77964514..cd5afc652c8 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/JvmPauseMonitor.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/JvmPauseMonitor.java
@@ -83,11 +83,13 @@ public class JvmPauseMonitor {
   
   public void stop() {
     shouldRun = false;
-    monitorThread.interrupt();
-    try {
-      monitorThread.join();
-    } catch (InterruptedException e) {
-      Thread.currentThread().interrupt();
+    if (monitorThread != null) {
+      monitorThread.interrupt();
+      try {
+        monitorThread.join();
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+      }
     }
   }
 
diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index c10fac41d24..0dcb6286115 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -71,6 +71,8 @@ Release 2.7.2 - UNRELEASED
     YARN-4096. App local logs are leaked if log aggregation fails to initialize
     for the app. (Jason Lowe via zxu)
 
+    YARN-4153. TestAsyncDispatcher failed at branch-2.7 (Zhihai Xu via jianhe)
+
 Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/event/AsyncDispatcher.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/event/AsyncDispatcher.java
index db4d3265c3e..6cdfaad839b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/event/AsyncDispatcher.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/event/AsyncDispatcher.java
@@ -144,9 +144,12 @@ public class AsyncDispatcher extends AbstractService implements Dispatcher {
               YarnConfiguration.DEFAULT_DISPATCHER_DRAIN_EVENTS_TIMEOUT);
 
       synchronized (waitForDrained) {
-        while (!drained && eventHandlingThread.isAlive()) {
+        while (!drained && eventHandlingThread != null
+            && eventHandlingThread.isAlive()
+            && System.currentTimeMillis() < endTime) {
           waitForDrained.wait(1000);
-          LOG.info("Waiting for AsyncDispatcher to drain.");
+          LOG.info("Waiting for AsyncDispatcher to drain. Thread state is :" +
+              eventHandlingThread.getState());
         }
       }
     }