MAPREDUCE-3313. Fixed initialization of ClusterMetrics which was failing TestResourceTrackerService sometimes. Contributed by Hitesh Shah.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1195319 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -1865,6 +1865,9 @@ Release 0.23.0 - Unreleased
     MAPREDUCE-3274. Fixed a race condition in MRAppMaster that was causing a
     task-scheduling deadlock. (Robert Joseph Evans via vinodkv)
 
+    MAPREDUCE-3313. Fixed initialization of ClusterMetrics which was failing
+    TestResourceTrackerService sometimes. (Hitesh Shah via vinodkv)
+
 Release 0.22.0 - Unreleased
 
   INCOMPATIBLE CHANGES

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/ClusterMetrics.java

@@ -20,6 +20,8 @@ package org.apache.hadoop.yarn.server.resourcemanager;
 
 import static org.apache.hadoop.metrics2.lib.Interns.info;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.metrics2.MetricsInfo;
 import org.apache.hadoop.metrics2.MetricsSystem;
@@ -35,6 +37,8 @@ import org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNodeEventType;
 @Metrics(context="yarn")
 public class ClusterMetrics {
   
+  private static AtomicBoolean isInitialized = new AtomicBoolean(false);
+  
   @Metric("# of NMs") MutableGaugeInt numNMs;
   @Metric("# of decommissioned NMs") MutableCounterInt numDecommissionedNMs;
   @Metric("# of lost NMs") MutableCounterInt numLostNMs;
@@ -48,11 +52,12 @@ public class ClusterMetrics {
   private static MetricsRegistry registry;
   
   public static ClusterMetrics getMetrics() {
-    if(INSTANCE == null){
+    if(!isInitialized.get()){
       synchronized (ClusterMetrics.class) {
         if(INSTANCE == null){
           INSTANCE = new ClusterMetrics();
           registerMetrics();
+          isInitialized.set(true);
         }
       }
     }

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/TestResourceTrackerService.java

@@ -31,7 +31,6 @@ import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.yarn.api.records.ApplicationId;
 import org.apache.hadoop.yarn.api.records.ContainerStatus;
 import org.apache.hadoop.yarn.api.records.NodeId;
-import org.apache.hadoop.yarn.exceptions.YarnRemoteException;
 import org.apache.hadoop.yarn.factories.RecordFactory;
 import org.apache.hadoop.yarn.factory.providers.RecordFactoryProvider;
 import org.apache.hadoop.yarn.server.api.protocolrecords.RegisterNodeManagerRequest;
@@ -67,8 +66,10 @@ public class TestResourceTrackerService {
 
     MockNM nm1 = rm.registerNode("host1:1234", 5120);
     MockNM nm2 = rm.registerNode("host2:5678", 10240);
-    int initialMetricCount = ClusterMetrics.getMetrics()
-        .getNumDecommisionedNMs();
+    
+    ClusterMetrics metrics = ClusterMetrics.getMetrics();
+    assert(metrics != null);
+    int initialMetricCount = metrics.getNumDecommisionedNMs();
 
     HeartbeatResponse nodeHeartbeat = nm1.nodeHeartbeat(true);
     Assert.assertTrue(NodeAction.NORMAL.equals(nodeHeartbeat.getNodeAction()));