HDFS-10367. TestDFSShell.testMoveWithTargetPortEmpty fails with Address bind exception. Contributed by Brahma Reddy Battula.

(cherry picked from commit aadb77e412)

 Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSShell.java

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/net/ServerSocketUtil.java

@@ -63,4 +63,43 @@ public class ServerSocketUtil {
     }
   }
 
+  /**
+   * Check whether port is available or not.
+   *
+   * @param port given port
+   * @return
+   */
+  private static boolean isPortAvailable(int port) {
+    try (ServerSocket s = new ServerSocket(port)) {
+      return true;
+    } catch (IOException e) {
+      return false;
+    }
+  }
+
+  /**
+   * Wait till the port available.
+   *
+   * @param port given port
+   * @param retries number of retries for given port
+   * @return
+   * @throws InterruptedException
+   * @throws IOException
+   */
+  public static int waitForPort(int port, int retries)
+      throws InterruptedException, IOException {
+    int tries = 0;
+    while (true) {
+      if (isPortAvailable(port)) {
+        return port;
+      } else {
+        tries++;
+        if (tries >= retries) {
+          throw new IOException(
+              "Port is already in use; giving up after " + tries + " times.");
+        }
+        Thread.sleep(1000);
+      }
+    }
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSShell.java

@@ -49,6 +49,7 @@ import org.apache.hadoop.io.SequenceFile;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.io.compress.BZip2Codec;
 import org.apache.hadoop.io.compress.CompressionCodec;
+import org.apache.hadoop.net.ServerSocketUtil;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.test.PathUtils;
 import org.apache.hadoop.util.ReflectionUtils;
@@ -530,7 +531,8 @@ public class TestDFSShell {
       cluster = new MiniDFSCluster.Builder(conf)
           .format(true)
           .numDataNodes(2)
-          .nameNodePort(8020)
+          .nameNodePort(ServerSocketUtil.waitForPort(
+              HdfsClientConfigKeys.DFS_NAMENODE_RPC_PORT_DEFAULT, 10))
           .waitSafeMode(true)
           .build();
       FileSystem srcFs = cluster.getFileSystem();