HDFS-10552. DiskBalancer "-query" results in NPE if no plan for the node. Contributed by Anu Engineer.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DiskBalancer.java

@@ -104,6 +104,7 @@ public class DiskBalancer {
     scheduler = Executors.newSingleThreadExecutor();
     lock = new ReentrantLock();
     workMap = new ConcurrentHashMap<>();
+    this.planID = "";  // to keep protobuf happy.
     this.isDiskBalancerEnabled = conf.getBoolean(
         DFSConfigKeys.DFS_DISK_BALANCER_ENABLED,
         DFSConfigKeys.DFS_DISK_BALANCER_ENABLED_DEFAULT);
@@ -223,7 +224,9 @@ public class DiskBalancer {
     lock.lock();
     try {
       checkDiskBalancerEnabled();
-      if ((this.planID == null) || (!this.planID.equals(planID))) {
+      if (this.planID == null ||
+          !this.planID.equals(planID) ||
+          this.planID.isEmpty()) {
         LOG.error("Disk Balancer - No such plan. Cancel plan failed. PlanID: " +
             planID);
         throw new DiskBalancerException("No such plan.",

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/command/QueryCommand.java

@@ -63,7 +63,7 @@ public class QueryCommand extends Command {
     String nodeAddress = nodeName;
 
     // if the string is not name:port format use the default port.
-    if (!nodeName.matches("^.*:\\d$")) {
+    if (!nodeName.matches("[^\\:]+:[0-9]{2,5}")) {
       int defaultIPC = NetUtils.createSocketAddr(
           getConf().getTrimmed(DFSConfigKeys.DFS_DATANODE_IPC_ADDRESS_KEY,
               DFSConfigKeys.DFS_DATANODE_IPC_ADDRESS_DEFAULT)).getPort();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/diskbalancer/command/TestDiskBalancerCommand.java

@@ -35,6 +35,7 @@ import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.server.datanode.DataNode;
 import org.apache.hadoop.hdfs.server.diskbalancer.connectors.ClusterConnector;
 import org.apache.hadoop.hdfs.server.diskbalancer.connectors.ConnectorFactory;
 import org.apache.hadoop.hdfs.server.diskbalancer.datamodel.DiskBalancerCluster;
@@ -351,4 +352,28 @@ public class TestDiskBalancerCommand {
     }
     return outputs;
   }
+
+  /**
+   * Making sure that we can query the node without having done a submit.
+   * @throws Exception
+   */
+  @Test
+  public void testDiskBalancerQueryWithoutSubmit() throws Exception {
+    Configuration conf = new HdfsConfiguration();
+    conf.setBoolean(DFSConfigKeys.DFS_DISK_BALANCER_ENABLED, true);
+    final int numDatanodes = 2;
+    MiniDFSCluster miniDFSCluster = new MiniDFSCluster.Builder(conf)
+        .numDataNodes(numDatanodes).build();
+    try {
+      miniDFSCluster.waitActive();
+      DataNode dataNode = miniDFSCluster.getDataNodes().get(0);
+      final String queryArg = String.format("-query localhost:%d", dataNode
+          .getIpcPort());
+      final String cmdLine = String.format("hdfs diskbalancer %s",
+          queryArg);
+      runCommand(cmdLine);
+    } finally {
+      miniDFSCluster.shutdown();
+    }
+  }
 }