commit 5de997c9ce0e6f5dcdc53a6d11ca8d655eba512f

Author: Hong Tang <htang@coatsatfind-lm.local>
Date:   Thu Aug 12 02:12:51 2010 -0700

    MAPREDUCE-1961. ConcurrentModificationException when shutting down Gridmix. From https://issues.apache.org/jira/secure/attachment/12450368/mr-1961-20100723.patch. (htang)
    
    +++ b/YAHOO-CHANGES.txt
    +    MAPREDUCE-1961. ConcurrentModificationException when shutting down Gridmix.
    +    (htang)
    +


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-patches@1077651 13f79535-47bb-0310-9956-ffa450edef68

src/contrib/gridmix/src/java/org/apache/hadoop/mapred/gridmix/Statistics.java

@@ -30,11 +30,11 @@ import org.apache.hadoop.tools.rumen.JobStory;
 
 import java.io.IOException;
 import java.security.PrivilegedExceptionAction;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.Condition;
@@ -56,11 +56,11 @@ public class Statistics implements Component<Job> {
 
   //List of cluster status listeners.
   private final List<StatListener<ClusterStats>> clusterStatlisteners =
-    new ArrayList<StatListener<ClusterStats>>();
+    new CopyOnWriteArrayList<StatListener<ClusterStats>>();
 
   //List of job status listeners.
   private final List<StatListener<JobStats>> jobStatListeners =
-    new ArrayList<StatListener<JobStats>>();
+    new CopyOnWriteArrayList<StatListener<JobStats>>();
 
   //List of jobids and noofMaps for each job
   private static final Map<Integer, JobStats> jobMaps =