svn merge -c 1215364 from trunk for HDFS-2694.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23-PB@1230899 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -91,6 +91,8 @@ Release 0.23-PB - Unreleased
     HDFS-2532. TestDfsOverAvroRpc timing out in trunk (Uma Maheswara Rao G
     via todd)
 
+    HDFS-2694. Removal of Avro broke non-PB NN services. (atm)
+
 Release 0.23.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -95,6 +95,7 @@ import org.apache.hadoop.ipc.ProtobufRpcEngine;
 import org.apache.hadoop.ipc.ProtocolSignature;
 import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.ipc.Server;
+import org.apache.hadoop.ipc.WritableRpcEngine;
 import org.apache.hadoop.ipc.RpcPayloadHeader.RpcKind;
 import org.apache.hadoop.net.Node;
 import org.apache.hadoop.security.AccessControlException;
@@ -162,6 +163,8 @@ class NameNodeRpcServer implements NamenodeProtocols {
 	  BlockingService NNPbService = NamenodeProtocolService
           .newReflectiveBlockingService(namenodeProtocolXlator);
     
+    WritableRpcEngine.ensureInitialized();
+    
     InetSocketAddress dnSocketAddr = nn.getServiceRpcServerAddress(conf);
     if (dnSocketAddr != null) {
       int serviceHandlerCount =