HDFS-9444. Add utility to find set of available ephemeral ports to ServerSocketUtil. Contributed by Masatake Iwasaki

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

@@ -102,4 +102,27 @@ public static int waitForPort(int port, int retries)
       }
     }
   }
+
+  /**
+   * Find the specified number of unique ports available.
+   * The ports are all closed afterwards,
+   * so other network services started may grab those same ports.
+   *
+   * @param numPorts number of required port nubmers
+   * @return array of available port numbers
+   * @throws IOException
+   */
+  public static int[] getPorts(int numPorts) throws IOException {
+    ServerSocket[] sockets = new ServerSocket[numPorts];
+    int[] ports = new int[numPorts];
+    for (int i = 0; i < numPorts; i++) {
+      ServerSocket sock = new ServerSocket(0);
+      sockets[i] = sock;
+      ports[i] = sock.getLocalPort();
+    }
+    for (ServerSocket sock : sockets) {
+      sock.close();
+    }
+    return ports;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java

@@ -47,6 +47,7 @@
 import javax.management.ObjectName;
 import java.io.File;
 import java.lang.management.ManagementFactory;
+import java.net.BindException;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -59,6 +60,7 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 /**
  * Class for testing {@link NameNodeMXBean} implementation
@@ -431,17 +433,29 @@ public void testQueueLength() throws Exception {
   public void testNNDirectorySize() throws Exception{
     Configuration conf = new Configuration();
     conf.setInt(DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_KEY, 1);
+    MiniDFSCluster cluster = null;
+    for (int i = 0; i < 5; i++) {
+      try{
         // Have to specify IPC ports so the NNs can talk to each other.
+        int[] ports = ServerSocketUtil.getPorts(2);
         MiniDFSNNTopology topology = new MiniDFSNNTopology()
             .addNameservice(new MiniDFSNNTopology.NSConf("ns1")
-            .addNN(new MiniDFSNNTopology.NNConf("nn1")
+                .addNN(new MiniDFSNNTopology.NNConf("nn1").setIpcPort(ports[0]))
-                .setIpcPort(ServerSocketUtil.getPort(0, 100)))
+                .addNN(
-            .addNN(new MiniDFSNNTopology.NNConf("nn2")
+                    new MiniDFSNNTopology.NNConf("nn2").setIpcPort(ports[1])));
-                .setIpcPort(ServerSocketUtil.getPort(0, 100))));
 
-    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
+        cluster = new MiniDFSCluster.Builder(conf)
             .nnTopology(topology).numDataNodes(0)
             .build();
+        break;
+      } catch (BindException e) {
+        // retry if race on ports given by ServerSocketUtil#getPorts
+        continue;
+      }
+    }
+    if (cluster == null) {
+      fail("failed to start mini cluster.");
+    }
     FileSystem fs = null;
     try {
       cluster.waitActive();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestEditLogTailer.java

@@ -24,6 +24,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.BindException;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -166,20 +167,33 @@ private static void testStandbyTriggersLogRolls(int activeIndex)
     conf.setInt(DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_KEY, 1);
     conf.setInt(DFSConfigKeys.DFS_HA_TAILEDITS_ALL_NAMESNODES_RETRY_KEY, 100);
 
+    MiniDFSCluster cluster = null;
+    for (int i = 0; i < 5; i++) {
+      try {
         // Have to specify IPC ports so the NNs can talk to each other.
+        int[] ports = ServerSocketUtil.getPorts(3);
         MiniDFSNNTopology topology = new MiniDFSNNTopology()
             .addNameservice(new MiniDFSNNTopology.NSConf("ns1")
                 .addNN(new MiniDFSNNTopology.NNConf("nn1")
-                .setIpcPort(ServerSocketUtil.getPort(0, 100)))
+                    .setIpcPort(ports[0]))
                 .addNN(new MiniDFSNNTopology.NNConf("nn2")
-                .setIpcPort(ServerSocketUtil.getPort(0, 100)))
+                    .setIpcPort(ports[1]))
                 .addNN(new MiniDFSNNTopology.NNConf("nn3")
-                .setIpcPort(ServerSocketUtil.getPort(0, 100))));
+                    .setIpcPort(ports[2])));
 
-    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
+        cluster = new MiniDFSCluster.Builder(conf)
           .nnTopology(topology)
           .numDataNodes(0)
           .build();
+        break;
+      } catch (BindException e) {
+        // retry if race on ports given by ServerSocketUtil#getPorts
+        continue;
+      }
+    }
+    if (cluster == null) {
+      fail("failed to start mini cluster.");
+    }
     try {
       cluster.transitionToActive(activeIndex);
       waitForLogRollInSharedDir(cluster, 3);