svn merge -c 1476487 FIXES: HADOOP-9504. MetricsDynamicMBeanBase has concurrency issues in createMBeanInfo. Contributed by Liang Xie

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1476489 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -21,6 +21,9 @@ Release 0.23.8 - UNRELEASED
     HADOOP-9469. mapreduce/yarn source jars not included in dist tarball
     (Robert Parker via tgraves)
 
+    HADOOP-9504. MetricsDynamicMBeanBase has concurrency issues in
+    createMBeanInfo (Liang Xie via jlowe)
+
 Release 0.23.7 - 2013-04-18
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics/util/MetricsDynamicMBeanBase.java

@@ -18,9 +18,9 @@
 package org.apache.hadoop.metrics.util;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import javax.management.Attribute;
 import javax.management.AttributeList;
@@ -69,6 +69,7 @@ public abstract class MetricsDynamicMBeanBase implements DynamicMBean {
   protected MetricsDynamicMBeanBase(final MetricsRegistry mr, final String aMBeanDescription) {
     metricsRegistry = mr;
     mbeanDescription = aMBeanDescription;
+    metricsRateAttributeMod = new ConcurrentHashMap<String, MetricsBase>();
     createMBeanInfo();
   }
   
@@ -78,7 +79,6 @@ public abstract class MetricsDynamicMBeanBase implements DynamicMBean {
   }
   
   private void createMBeanInfo() {
-    metricsRateAttributeMod = new HashMap<String, MetricsBase>();
     boolean needsMinMaxResetOperation = false;
     List<MBeanAttributeInfo> attributesInfo = new ArrayList<MBeanAttributeInfo>();
     MBeanOperationInfo[] operationsInfo = null;