svn merge -c 1164771 from trunk for MAPREDUCE-2887.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23-PB@1228671 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -1,8 +1,12 @@
 Hadoop MapReduce Change Log
 
-Release 0.23.1 - Unreleased
+Release 0.23-PB - Unreleased
 
-  INCOMPATIBLE CHANGES
+  IMPROVEMENTS
+
+    MAPREDUCE-2887 due to HADOOP-7524 Change RPC to allow multiple protocols including multuple versions of the same protocol (sanjay Radia)
+
+Release 0.23.1 - Unreleased
 
   NEW FEATURES                                                                    
 

hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/ipc/ProtoOverHadoopRpcEngine.java

@@ -318,15 +318,15 @@ public class ProtoOverHadoopRpcEngine implements RpcEngine {
     }
 
     @Override
-    public Writable call(Class<?> protocol, Writable writableRequest,
+    public Writable call(String protocol, Writable writableRequest,
         long receiveTime) throws IOException {
       ProtoSpecificRequestWritable request = (ProtoSpecificRequestWritable) writableRequest;
       ProtoSpecificRpcRequest rpcRequest = request.message;
       String methodName = rpcRequest.getMethodName();
-      System.out.println("Call: protocol=" + protocol.getCanonicalName() + ", method="
+      System.out.println("Call: protocol=" + protocol + ", method="
           + methodName);
       if (verbose)
-        log("Call: protocol=" + protocol.getCanonicalName() + ", method="
+        log("Call: protocol=" + protocol + ", method="
             + methodName);
       MethodDescriptor methodDescriptor = service.getDescriptorForType()
           .findMethodByName(methodName);

hadoop-mapreduce-project/src/java/org/apache/hadoop/mapred/JobTracker.java

@@ -1484,7 +1484,7 @@ public class JobTracker implements MRConstants, InterTrackerProtocol,
     taskScheduler = (TaskScheduler) ReflectionUtils.newInstance(schedulerClass, conf);
     
     int handlerCount = conf.getInt(JT_IPC_HANDLER_COUNT, 10);
-    this.interTrackerServer = RPC.getServer(ClientProtocol.class,
+    this.interTrackerServer = RPC.getServer(JobTracker.class, // All protocols in JobTracker
                                             this,
                                             addr.getHostName(), 
                                             addr.getPort(), handlerCount,