HDFS-11533. reuseAddress option should be used for child channels in Portmap and SimpleTcpServer. Contributed by Mukul Kumar Singh.

hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/oncrpc/SimpleTcpServer.java

@@ -81,6 +81,7 @@ public class SimpleTcpServer {
     });
     server.setOption("child.tcpNoDelay", true);
     server.setOption("child.keepAlive", true);
+    server.setOption("child.reuseAddress", true);
     server.setOption("reuseAddress", true);
 
     // Listen to TCP port

hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/portmap/Portmap.java

@@ -110,6 +110,7 @@ final class Portmap {
       }
     });
     tcpServer.setOption("reuseAddress", true);
+    tcpServer.setOption("child.reuseAddress", true);
 
     udpServer = new ConnectionlessBootstrap(new NioDatagramChannelFactory(
         Executors.newCachedThreadPool()));