MAPREDUCE-3443. JobClient and Job should function in the context of the UGI which created them. (Contributed by Mahadev Konar)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1209231 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -211,6 +211,9 @@ Release 0.23.1 - Unreleased
     MAPREDUCE-3452. fifoscheduler web ui page always shows 0% used for the queue.
     (Jonathan Eagles via mahadev)
 
+    MAPREDUCE-3443. JobClient and Job should function in the context of the
+    UGI which created them. (Mahadev Konar via sseth)
+
 Release 0.23.0 - 2011-11-01 
 
   INCOMPATIBLE CHANGES

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/JobClient.java

@@ -21,6 +21,7 @@ import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.URL;
+import java.security.PrivilegedExceptionAction;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -42,6 +43,7 @@ import org.apache.hadoop.mapreduce.util.ConfigUtil;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenRenewer;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
@@ -421,6 +423,11 @@ public class JobClient extends CLI {
   }
 
   Cluster cluster;
+  /**
+   * Ugi of the client. We store this ugi when the client is created and 
+   * then make sure that the same ugi is used to run the various protocols.
+   */
+  UserGroupInformation clientUgi;
   
   /**
    * Create a job client.
@@ -458,6 +465,7 @@ public class JobClient extends CLI {
   public void init(JobConf conf) throws IOException {
     setConf(conf);
     cluster = new Cluster(conf);
+    clientUgi = UserGroupInformation.getCurrentUser();
   }
 
   @InterfaceAudience.Private
@@ -487,8 +495,7 @@ public class JobClient extends CLI {
     @Override
     public boolean isManaged(Token<?> token) throws IOException {
       return true;
-    }
-    
+    }   
   }
 
   /**
@@ -500,6 +507,7 @@ public class JobClient extends CLI {
   public JobClient(InetSocketAddress jobTrackAddr, 
                    Configuration conf) throws IOException {
     cluster = new Cluster(jobTrackAddr, conf);
+    clientUgi = UserGroupInformation.getCurrentUser();
   }
 
   /**
@@ -562,21 +570,34 @@ public class JobClient extends CLI {
    * @throws FileNotFoundException
    * @throws IOException
    */
-  public RunningJob submitJob(JobConf conf) throws FileNotFoundException,
+  public RunningJob submitJob(final JobConf conf) throws FileNotFoundException,
                                                   IOException {
     try {
       conf.setBooleanIfUnset("mapred.mapper.new-api", false);
       conf.setBooleanIfUnset("mapred.reducer.new-api", false);
-      Job job = Job.getInstance(conf);
-      job.submit();
+      Job job = clientUgi.doAs(new PrivilegedExceptionAction<Job> () {
+        @Override
+        public Job run() throws IOException, ClassNotFoundException, 
+          InterruptedException {
+          Job job = Job.getInstance(conf);
+          job.submit();
+          return job;
+        }
+      });
       return new NetworkedJob(job);
     } catch (InterruptedException ie) {
       throw new IOException("interrupted", ie);
-    } catch (ClassNotFoundException cnfe) {
-      throw new IOException("class not found", cnfe);
     }
   }
 
+  private Job getJobUsingCluster(final JobID jobid) throws IOException,
+  InterruptedException {
+    return clientUgi.doAs(new PrivilegedExceptionAction<Job>() {
+      public Job run() throws IOException, InterruptedException  {
+       return cluster.getJob(jobid);
+      }
+    });
+  }
   /**
    * Get an {@link RunningJob} object to track an ongoing job.  Returns
    * null if the id does not correspond to any known job.
@@ -586,9 +607,10 @@ public class JobClient extends CLI {
    *         <code>jobid</code> doesn't correspond to any known job.
    * @throws IOException
    */
-  public RunningJob getJob(JobID jobid) throws IOException {
+  public RunningJob getJob(final JobID jobid) throws IOException {
     try {
-      Job job = cluster.getJob(jobid);
+      
+      Job job = getJobUsingCluster(jobid);
       if (job != null) {
         JobStatus status = JobStatus.downgrade(job.getStatus());
         if (status != null) {
@@ -621,9 +643,10 @@ public class JobClient extends CLI {
     return getTaskReports(jobId, TaskType.MAP);
   }
   
-  private TaskReport[] getTaskReports(JobID jobId, TaskType type) throws IOException {
+  private TaskReport[] getTaskReports(final JobID jobId, TaskType type) throws 
+    IOException {
     try {
-      Job j = cluster.getJob(jobId);
+      Job j = getJobUsingCluster(jobId);
       if(j == null) {
         return EMPTY_TASK_REPORTS;
       }
@@ -688,10 +711,11 @@ public class JobClient extends CLI {
    * @param state the state of the task 
    * (pending/running/completed/failed/killed)
    */
-  public void displayTasks(JobID jobId, String type, String state) 
+  public void displayTasks(final JobID jobId, String type, String state) 
   throws IOException {
     try {
-      super.displayTasks(cluster.getJob(jobId), type, state);
+      Job job = getJobUsingCluster(jobId);
+      super.displayTasks(job, type, state);
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -706,15 +730,20 @@ public class JobClient extends CLI {
    */
   public ClusterStatus getClusterStatus() throws IOException {
     try {
-      ClusterMetrics metrics = cluster.getClusterStatus();
-      return new ClusterStatus(metrics.getTaskTrackerCount(),
-        metrics.getBlackListedTaskTrackerCount(), cluster.getTaskTrackerExpiryInterval(),
-        metrics.getOccupiedMapSlots(),
-        metrics.getOccupiedReduceSlots(), metrics.getMapSlotCapacity(),
-        metrics.getReduceSlotCapacity(),
-        cluster.getJobTrackerStatus(),
-        metrics.getDecommissionedTaskTrackerCount());
-    } catch (InterruptedException ie) {
+      return clientUgi.doAs(new PrivilegedExceptionAction<ClusterStatus>() {
+        public ClusterStatus run()  throws IOException, InterruptedException {
+          ClusterMetrics metrics = cluster.getClusterStatus();
+          return new ClusterStatus(metrics.getTaskTrackerCount(),
+              metrics.getBlackListedTaskTrackerCount(), cluster.getTaskTrackerExpiryInterval(),
+              metrics.getOccupiedMapSlots(),
+              metrics.getOccupiedReduceSlots(), metrics.getMapSlotCapacity(),
+              metrics.getReduceSlotCapacity(),
+              cluster.getJobTrackerStatus(),
+              metrics.getDecommissionedTaskTrackerCount());
+        }
+      });
+    }
+      catch (InterruptedException ie) {
       throw new IOException(ie);
     }
   }
@@ -750,13 +779,17 @@ public class JobClient extends CLI {
    */
   public ClusterStatus getClusterStatus(boolean detailed) throws IOException {
     try {
-      ClusterMetrics metrics = cluster.getClusterStatus();
-      return new ClusterStatus(arrayToStringList(cluster.getActiveTaskTrackers()),
-        arrayToBlackListInfo(cluster.getBlackListedTaskTrackers()),
-        cluster.getTaskTrackerExpiryInterval(), metrics.getOccupiedMapSlots(),
-        metrics.getOccupiedReduceSlots(), metrics.getMapSlotCapacity(),
-        metrics.getReduceSlotCapacity(), 
-        cluster.getJobTrackerStatus());
+      return clientUgi.doAs(new PrivilegedExceptionAction<ClusterStatus>() {
+        public ClusterStatus run() throws IOException, InterruptedException {
+        ClusterMetrics metrics = cluster.getClusterStatus();
+        return new ClusterStatus(arrayToStringList(cluster.getActiveTaskTrackers()),
+          arrayToBlackListInfo(cluster.getBlackListedTaskTrackers()),
+          cluster.getTaskTrackerExpiryInterval(), metrics.getOccupiedMapSlots(),
+          metrics.getOccupiedReduceSlots(), metrics.getMapSlotCapacity(),
+          metrics.getReduceSlotCapacity(), 
+          cluster.getJobTrackerStatus());
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -787,7 +820,14 @@ public class JobClient extends CLI {
    */
   public JobStatus[] getAllJobs() throws IOException {
     try {
-      org.apache.hadoop.mapreduce.JobStatus[] jobs = cluster.getAllJobStatuses();
+      org.apache.hadoop.mapreduce.JobStatus[] jobs = 
+          clientUgi.doAs(new PrivilegedExceptionAction<
+              org.apache.hadoop.mapreduce.JobStatus[]> () {
+            public org.apache.hadoop.mapreduce.JobStatus[] run() 
+                throws IOException, InterruptedException {
+              return cluster.getAllJobStatuses();
+            }
+          });
       JobStatus[] stats = new JobStatus[jobs.length];
       for (int i = 0; i < jobs.length; i++) {
         stats[i] = JobStatus.downgrade(jobs[i]);
@@ -909,7 +949,12 @@ public class JobClient extends CLI {
    */
   public int getDefaultMaps() throws IOException {
     try {
-      return cluster.getClusterStatus().getMapSlotCapacity();
+      return clientUgi.doAs(new PrivilegedExceptionAction<Integer>() {
+        @Override
+        public Integer run() throws IOException, InterruptedException {
+          return cluster.getClusterStatus().getMapSlotCapacity();
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -923,7 +968,12 @@ public class JobClient extends CLI {
    */
   public int getDefaultReduces() throws IOException {
     try {
-      return cluster.getClusterStatus().getReduceSlotCapacity();
+      return clientUgi.doAs(new PrivilegedExceptionAction<Integer>() {
+        @Override
+        public Integer run() throws IOException, InterruptedException {
+          return cluster.getClusterStatus().getReduceSlotCapacity();
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -936,8 +986,13 @@ public class JobClient extends CLI {
    */
   public Path getSystemDir() {
     try {
-      return cluster.getSystemDir();
-    } catch (IOException ioe) {
+      return clientUgi.doAs(new PrivilegedExceptionAction<Path>() {
+        @Override
+        public Path run() throws IOException, InterruptedException {
+          return cluster.getSystemDir();
+        }
+      });
+      } catch (IOException ioe) {
       return null;
     } catch (InterruptedException ie) {
       return null;
@@ -962,7 +1017,11 @@ public class JobClient extends CLI {
    */
   public JobQueueInfo[] getRootQueues() throws IOException {
     try {
-      return getJobQueueInfoArray(cluster.getRootQueues());
+      return clientUgi.doAs(new PrivilegedExceptionAction<JobQueueInfo[]>() {
+        public JobQueueInfo[] run() throws IOException, InterruptedException {
+          return getJobQueueInfoArray(cluster.getRootQueues());
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -976,9 +1035,13 @@ public class JobClient extends CLI {
    * @return the array of immediate children JobQueueInfo objects
    * @throws IOException
    */
-  public JobQueueInfo[] getChildQueues(String queueName) throws IOException {
+  public JobQueueInfo[] getChildQueues(final String queueName) throws IOException {
     try {
-      return getJobQueueInfoArray(cluster.getChildQueues(queueName));
+      return clientUgi.doAs(new PrivilegedExceptionAction<JobQueueInfo[]>() {
+        public JobQueueInfo[] run() throws IOException, InterruptedException {
+          return getJobQueueInfoArray(cluster.getChildQueues(queueName));
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -993,7 +1056,11 @@ public class JobClient extends CLI {
    */
   public JobQueueInfo[] getQueues() throws IOException {
     try {
-      return getJobQueueInfoArray(cluster.getQueues());
+      return clientUgi.doAs(new PrivilegedExceptionAction<JobQueueInfo[]>() {
+        public JobQueueInfo[] run() throws IOException, InterruptedException {
+          return getJobQueueInfoArray(cluster.getQueues());
+        }
+      });
     } catch (InterruptedException ie) {
       throw new IOException(ie);
     }
@@ -1007,9 +1074,14 @@ public class JobClient extends CLI {
    * @throws IOException
    */
   
-  public JobStatus[] getJobsFromQueue(String queueName) throws IOException {
+  public JobStatus[] getJobsFromQueue(final String queueName) throws IOException {
     try {
-      QueueInfo queue = cluster.getQueue(queueName);
+      QueueInfo queue = clientUgi.doAs(new PrivilegedExceptionAction<QueueInfo>() {
+        @Override
+        public QueueInfo run() throws IOException, InterruptedException {
+          return cluster.getQueue(queueName);
+        }
+      });
       if (queue == null) {
         return null;
       }
@@ -1032,9 +1104,14 @@ public class JobClient extends CLI {
    * @return Queue information associated to particular queue.
    * @throws IOException
    */
-  public JobQueueInfo getQueueInfo(String queueName) throws IOException {
+  public JobQueueInfo getQueueInfo(final String queueName) throws IOException {
     try {
-      QueueInfo queueInfo = cluster.getQueue(queueName);
+      QueueInfo queueInfo = clientUgi.doAs(new 
+          PrivilegedExceptionAction<QueueInfo>() {
+        public QueueInfo run() throws IOException, InterruptedException {
+          return cluster.getQueue(queueName);
+        }
+      });
       if (queueInfo != null) {
         return new JobQueueInfo(queueInfo);
       }
@@ -1052,7 +1129,14 @@ public class JobClient extends CLI {
   public QueueAclsInfo[] getQueueAclsForCurrentUser() throws IOException {
     try {
       org.apache.hadoop.mapreduce.QueueAclsInfo[] acls = 
-        cluster.getQueueAclsForCurrentUser();
+        clientUgi.doAs(new 
+            PrivilegedExceptionAction
+            <org.apache.hadoop.mapreduce.QueueAclsInfo[]>() {
+              public org.apache.hadoop.mapreduce.QueueAclsInfo[] run() 
+              throws IOException, InterruptedException {
+                return cluster.getQueueAclsForCurrentUser();
+              }
+        });
       QueueAclsInfo[] ret = new QueueAclsInfo[acls.length];
       for (int i = 0 ; i < acls.length; i++ ) {
         ret[i] = QueueAclsInfo.downgrade(acls[i]);
@@ -1070,8 +1154,14 @@ public class JobClient extends CLI {
    * @throws IOException
    */
   public Token<DelegationTokenIdentifier> 
-    getDelegationToken(Text renewer) throws IOException, InterruptedException {
-    return cluster.getDelegationToken(renewer);
+    getDelegationToken(final Text renewer) throws IOException, InterruptedException {
+    return clientUgi.doAs(new 
+        PrivilegedExceptionAction<Token<DelegationTokenIdentifier>>() {
+      public Token<DelegationTokenIdentifier> run() throws IOException, 
+      InterruptedException {
+        return cluster.getDelegationToken(renewer);
+      }
+    });
   }
 
   /**

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/Job.java

@@ -30,6 +30,7 @@ import java.net.URL;
 import java.net.URLConnection;
 import java.net.URI;
 import java.security.PrivilegedExceptionAction;
+import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -315,7 +316,12 @@ public class Job extends JobContextImpl implements JobContext {
    * @throws IOException
    */
   synchronized void updateStatus() throws IOException, InterruptedException {
-    this.status = cluster.getClient().getJobStatus(status.getJobID());
+    this.status = ugi.doAs(new PrivilegedExceptionAction<JobStatus>() {
+      @Override
+      public JobStatus run() throws IOException, InterruptedException {
+        return cluster.getClient().getJobStatus(status.getJobID());
+      }
+    });
     if (this.status == null) {
       throw new IOException("Job status not available ");
     }
@@ -476,8 +482,16 @@ public class Job extends JobContextImpl implements JobContext {
       InterruptedException {
     int failCount = 1;
     TaskCompletionEvent lastEvent = null;
-    for (TaskCompletionEvent event : cluster.getClient().getTaskCompletionEvents(
-        status.getJobID(), 0, 10)) {
+    TaskCompletionEvent[] events = ugi.doAs(new 
+        PrivilegedExceptionAction<TaskCompletionEvent[]>() {
+          @Override
+          public TaskCompletionEvent[] run() throws IOException,
+          InterruptedException {
+            return cluster.getClient().getTaskCompletionEvents(
+                status.getJobID(), 0, 10);
+          }
+        });
+    for (TaskCompletionEvent event : events) {
       if (event.getStatus().equals(TaskCompletionEvent.Status.FAILED)) {
         failCount++;
         lastEvent = event;
@@ -500,7 +514,12 @@ public class Job extends JobContextImpl implements JobContext {
   public TaskReport[] getTaskReports(TaskType type) 
       throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().getTaskReports(getJobID(), type);
+    final TaskType tmpType = type;
+    return ugi.doAs(new PrivilegedExceptionAction<TaskReport[]>() {
+      public TaskReport[] run() throws IOException, InterruptedException {
+        return cluster.getClient().getTaskReports(getJobID(), tmpType);
+      }
+    });
   }
 
   /**
@@ -603,7 +622,14 @@ public class Job extends JobContextImpl implements JobContext {
         org.apache.hadoop.mapred.JobPriority.valueOf(priority.name()));
     } else {
       ensureState(JobState.RUNNING);
-      cluster.getClient().setJobPriority(getJobID(), priority.toString());
+      final JobPriority tmpPriority = priority;
+      ugi.doAs(new PrivilegedExceptionAction<Object>() {
+        @Override
+        public Object run() throws IOException, InterruptedException {
+          cluster.getClient().setJobPriority(getJobID(), tmpPriority.toString());
+          return null;
+        }
+      });
     }
   }
 
@@ -615,12 +641,17 @@ public class Job extends JobContextImpl implements JobContext {
    * @return an array of {@link TaskCompletionEvent}s
    * @throws IOException
    */
-  public TaskCompletionEvent[] getTaskCompletionEvents(int startFrom,
-      int numEvents) throws IOException, InterruptedException {
+  public TaskCompletionEvent[] getTaskCompletionEvents(final int startFrom,
+      final int numEvents) throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().getTaskCompletionEvents(getJobID(),
-      startFrom, numEvents); 
-  }
+    return ugi.doAs(new PrivilegedExceptionAction<TaskCompletionEvent[]>() {
+      @Override
+      public TaskCompletionEvent[] run() throws IOException, InterruptedException {
+        return cluster.getClient().getTaskCompletionEvents(getJobID(),
+            startFrom, numEvents); 
+      }
+    });
+    }
   
   /**
    * Kill indicated task attempt.
@@ -628,10 +659,14 @@ public class Job extends JobContextImpl implements JobContext {
    * @param taskId the id of the task to be terminated.
    * @throws IOException
    */
-  public boolean killTask(TaskAttemptID taskId) 
+  public boolean killTask(final TaskAttemptID taskId) 
       throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().killTask(taskId, false);
+    return ugi.doAs(new PrivilegedExceptionAction<Boolean>() {
+      public Boolean run() throws IOException, InterruptedException {
+        return cluster.getClient().killTask(taskId, false);
+      }
+    });
   }
 
   /**
@@ -640,10 +675,15 @@ public class Job extends JobContextImpl implements JobContext {
    * @param taskId the id of the task to be terminated.
    * @throws IOException
    */
-  public boolean failTask(TaskAttemptID taskId) 
+  public boolean failTask(final TaskAttemptID taskId) 
       throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().killTask(taskId, true);
+    return ugi.doAs(new PrivilegedExceptionAction<Boolean>() {
+      @Override
+      public Boolean run() throws IOException, InterruptedException {
+        return cluster.getClient().killTask(taskId, true);
+      }
+    });
   }
 
   /**
@@ -656,7 +696,12 @@ public class Job extends JobContextImpl implements JobContext {
   public Counters getCounters() 
       throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().getJobCounters(getJobID());
+    return ugi.doAs(new PrivilegedExceptionAction<Counters>() {
+      @Override
+      public Counters run() throws IOException, InterruptedException {
+        return cluster.getClient().getJobCounters(getJobID());
+      }
+    });
   }
 
   /**
@@ -665,10 +710,15 @@ public class Job extends JobContextImpl implements JobContext {
    * @return the list of diagnostic messages for the task
    * @throws IOException
    */
-  public String[] getTaskDiagnostics(TaskAttemptID taskid) 
+  public String[] getTaskDiagnostics(final TaskAttemptID taskid) 
       throws IOException, InterruptedException {
     ensureState(JobState.RUNNING);
-    return cluster.getClient().getTaskDiagnostics(taskid);
+    return ugi.doAs(new PrivilegedExceptionAction<String[]>() {
+      @Override
+      public String[] run() throws IOException, InterruptedException {
+        return cluster.getClient().getTaskDiagnostics(taskid);
+      }
+    });
   }
 
   /**

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/main/java/org/apache/hadoop/mapred/ClientServiceDelegate.java

@@ -22,7 +22,7 @@ import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.InetSocketAddress;
-import java.security.PrivilegedAction;
+import java.security.PrivilegedExceptionAction;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.List;
@@ -156,6 +156,8 @@ public class ClientServiceDelegate {
           application = rm.getApplicationReport(appId);
           continue;
         }
+        UserGroupInformation newUgi = UserGroupInformation.createRemoteUser(
+            UserGroupInformation.getCurrentUser().getUserName());
         serviceAddr = application.getHost() + ":" + application.getRpcPort();
         if (UserGroupInformation.isSecurityEnabled()) {
           String clientTokenEncoded = application.getClientToken();
@@ -167,11 +169,17 @@ public class ClientServiceDelegate {
               .getHost(), application.getRpcPort());
           clientToken.setService(new Text(addr.getAddress().getHostAddress()
               + ":" + addr.getPort()));
-          UserGroupInformation.getCurrentUser().addToken(clientToken);
+          newUgi.addToken(clientToken);
         }
         LOG.info("The url to track the job: " + application.getTrackingUrl());
         LOG.debug("Connecting to " + serviceAddr);
-        realProxy = instantiateAMProxy(serviceAddr);
+        final String tempStr = serviceAddr;
+        realProxy = newUgi.doAs(new PrivilegedExceptionAction<MRClientProtocol>() {
+          @Override
+          public MRClientProtocol run() throws IOException {
+            return instantiateAMProxy(tempStr);
+          }
+        });
         return realProxy;
       } catch (IOException e) {
         //possibly the AM has crashed
@@ -243,17 +251,11 @@ public class ClientServiceDelegate {
 
   MRClientProtocol instantiateAMProxy(final String serviceAddr)
       throws IOException {
-    UserGroupInformation currentUser = UserGroupInformation.getCurrentUser();
     LOG.trace("Connecting to ApplicationMaster at: " + serviceAddr);
-    MRClientProtocol proxy = currentUser
-        .doAs(new PrivilegedAction<MRClientProtocol>() {
-      @Override
-      public MRClientProtocol run() {
-        YarnRPC rpc = YarnRPC.create(conf);
-        return (MRClientProtocol) rpc.getProxy(MRClientProtocol.class,
+    YarnRPC rpc = YarnRPC.create(conf);
+    MRClientProtocol proxy = 
+         (MRClientProtocol) rpc.getProxy(MRClientProtocol.class,
             NetUtils.createSocketAddr(serviceAddr), conf);
-      }
-    });
     LOG.trace("Connected to ApplicationMaster at: " + serviceAddr);
     return proxy;
   }