HADOOP-9559. When metrics system is restarted MBean names get incorrectly flagged as dupes. Contributed by Mostafa Elhemali and Mike Liddell.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1604225 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -582,6 +582,9 @@ Release 2.5.0 - UNRELEASED
     HADOOP-10716. Cannot use more than 1 har filesystem.
     (Rushabh Shah via cnauroth)
 
+    HADOOP-9559. When metrics system is restarted MBean names get incorrectly
+    flagged as dupes. (Mostafa Elhemali and Mike Liddell via cnauroth)
+
   BREAKDOWN OF HADOOP-10514 SUBTASKS AND RELATED JIRAS
 
     HADOOP-10520. Extended attributes definition and FileSystem APIs for

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/impl/MetricsSourceAdapter.java

@@ -30,6 +30,7 @@
 import javax.management.ReflectionException;
 
 import static com.google.common.base.Preconditions.*;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.Maps;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -226,7 +227,13 @@ synchronized void stopMBeans() {
       mbeanName = null;
     }
   }
+  
+  @VisibleForTesting
+  ObjectName getMBeanName() {
+    return mbeanName;
+  }
 
+  
   private void updateInfoCache() {
     LOG.debug("Updating info cache...");
     infoCache = infoBuilder.reset(lastRecs).get();

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/impl/MetricsSystemImpl.java

@@ -32,6 +32,7 @@
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.common.annotations.VisibleForTesting;
 import java.util.Locale;
 import static com.google.common.base.Preconditions.*;
 
@@ -573,6 +574,11 @@ public MetricsSource getSource(String name) {
     return allSources.get(name);
   }
 
+  @VisibleForTesting
+  MetricsSourceAdapter getSourceAdapter(String name) {
+    return sources.get(name);
+  }
+
   private InitMode initMode() {
     LOG.debug("from system property: "+ System.getProperty(MS_INIT_MODE_KEY));
     LOG.debug("from environment variable: "+ System.getenv(MS_INIT_MODE_KEY));

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/lib/DefaultMetricsSystem.java

@@ -110,6 +110,11 @@ public static ObjectName newMBeanName(String name) {
     return INSTANCE.newObjectName(name);
   }
 
+  @InterfaceAudience.Private
+  public static void removeMBeanName(ObjectName name) {
+    INSTANCE.removeObjectName(name.toString());
+  }
+
   @InterfaceAudience.Private
   public static String sourceName(String name, boolean dupOK) {
     return INSTANCE.newSourceName(name, dupOK);
@@ -126,6 +131,10 @@ synchronized ObjectName newObjectName(String name) {
     }
   }
 
+  synchronized void removeObjectName(String name) {
+    mBeanNames.map.remove(name);
+  }
+
   synchronized String newSourceName(String name, boolean dupOK) {
     if (sourceNames.map.containsKey(name)) {
       if (dupOK) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/util/MBeans.java

@@ -84,6 +84,7 @@ static public void unregister(ObjectName mbeanName) {
     } catch (Exception e) {
       LOG.warn("Error unregistering "+ mbeanName, e);
     }
+    DefaultMetricsSystem.removeMBeanName(mbeanName);
   }
 
   static private ObjectName getMBeanName(String serviceName, String nameName) {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/metrics2/impl/TestMetricsSystemImpl.java

@@ -360,6 +360,24 @@ public void flush() {
     ms.register(ts);
   }
 
+  @Test public void testStartStopStart() {
+    DefaultMetricsSystem.shutdown(); // Clear pre-existing source names.
+    MetricsSystemImpl ms = new MetricsSystemImpl("test");
+    TestSource ts = new TestSource("ts");
+    ms.start();
+    ms.register("ts", "", ts);
+    MetricsSourceAdapter sa = ms.getSourceAdapter("ts");
+    assertNotNull(sa);
+    assertNotNull(sa.getMBeanName());
+    ms.stop();
+    ms.shutdown();
+    ms.start();
+    sa = ms.getSourceAdapter("ts");
+    assertNotNull(sa);
+    assertNotNull(sa.getMBeanName());
+    ms.stop();
+    ms.shutdown();
+  }
 
   private void checkMetricsRecords(List<MetricsRecord> recs) {
     LOG.debug(recs);