先走到
hadoop-common-project\hadoop-common\src\main\java\org\apache\hadoop\ipc\Server.java
的Handler类的run方法里的

call(call.rpcKind, call.connection.protocolName, call.rpcRequest, 
                           call.timestamp);

然后走到

ClientNamenodeProtocolProtos.java的 
 public static com.google.protobuf.BlockingService 
 newReflectiveBlockingService(final BlockingInterface impl)

方法