HDFS-13715:diskbalancer does not work if one of the blockpools are empty on a Federated cluster. Contributed by Bharat Viswanadham

(cherry picked from commit 59a3038bc3)

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

@@ -18,6 +18,7 @@
  */
 package org.apache.hadoop.hdfs.server.datanode;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import org.apache.commons.codec.digest.DigestUtils;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -77,7 +78,8 @@ import static java.util.concurrent.TimeUnit.SECONDS;
 @InterfaceAudience.Private
 public class DiskBalancer {
 
-  private static final Logger LOG = LoggerFactory.getLogger(DiskBalancer
+  @VisibleForTesting
+  public static final Logger LOG = LoggerFactory.getLogger(DiskBalancer
       .class);
   private final FsDatasetSpi<?> dataset;
   private final String dataNodeUUID;
@@ -902,15 +904,19 @@ public class DiskBalancer {
         try {
           ExtendedBlock block = iter.nextBlock();
 
-          // A valid block is a finalized block, we iterate until we get
+          if (block != null) {
-          // finalized blocks
+            // A valid block is a finalized block, we iterate until we get
-          if (!this.dataset.isValidBlock(block)) {
+            // finalized blocks
-            continue;
+            if (!this.dataset.isValidBlock(block)) {
-          }
+              continue;
+            }
 
-          // We don't look for the best, we just do first fit
+            // We don't look for the best, we just do first fit
-          if (isLessThanNeeded(block.getNumBytes(), item)) {
+            if (isLessThanNeeded(block.getNumBytes(), item)) {
-            return block;
+              return block;
+            }
+          } else {
+            LOG.info("There are no blocks in the blockPool {}", iter.getBlockPoolId());
           }
 
         } catch (IOException e) {
@@ -1126,6 +1132,11 @@ public class DiskBalancer {
             Thread.currentThread().interrupt();
             item.incErrorCount();
             this.setExitFlag();
+          } catch (RuntimeException ex) {
+            // Exiting if any run time exceptions.
+            LOG.error("Got an unexpected Runtime Exception {}", ex);
+            item.incErrorCount();
+            this.setExitFlag();
           }
         }
       } finally {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -1927,6 +1927,10 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
    */
   @Override // FsDatasetSpi
   public boolean isValidBlock(ExtendedBlock b) {
+    // If block passed is null, we should return false.
+    if (b == null) {
+      return false;
+    }
     return isValid(b, ReplicaState.FINALIZED);
   }
   
@@ -1935,6 +1939,10 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
    */
   @Override // {@link FsDatasetSpi}
   public boolean isValidRbw(final ExtendedBlock b) {
+    // If block passed is null, we should return false.
+    if (b == null) {
+      return false;
+    }
     return isValid(b, ReplicaState.RBW);
   }
 

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

@@ -154,7 +154,7 @@ public class TestDiskBalancer {
       NodePlan plan = dataMover.generatePlan();
       dataMover.executePlan(plan);
       dataMover.verifyPlanExectionDone();
-      dataMover.verifyAllVolumesHaveData();
+      dataMover.verifyAllVolumesHaveData(true);
       dataMover.verifyTolerance(plan, 0, sourceDiskIndex, 10);
     } finally {
       cluster.shutdown();
@@ -209,7 +209,7 @@ public class TestDiskBalancer {
       NodePlan plan = dataMover.generatePlan();
       dataMover.executePlan(plan);
       dataMover.verifyPlanExectionDone();
-      dataMover.verifyAllVolumesHaveData();
+      dataMover.verifyAllVolumesHaveData(true);
       dataMover.verifyTolerance(plan, 0, sourceDiskIndex, 10);
     } finally {
       cluster.shutdown();
@@ -217,6 +217,66 @@ public class TestDiskBalancer {
 
   }
 
+
+  @Test
+  public void testDiskBalancerWithFedClusterWithOneNameServiceEmpty() throws
+      Exception {
+    Configuration conf = new HdfsConfiguration();
+    conf.setBoolean(DFSConfigKeys.DFS_DISK_BALANCER_ENABLED, true);
+    final int blockCount = 100;
+    final int blockSize = 1024;
+    final int diskCount = 2;
+    final int dataNodeCount = 1;
+    final int dataNodeIndex = 0;
+    final int sourceDiskIndex = 0;
+    final long cap = blockSize * 3L * blockCount;
+
+    conf.setInt(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, blockSize);
+    conf.setInt(DFSConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY, blockSize);
+
+    final MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
+        .nnTopology(MiniDFSNNTopology.simpleFederatedTopology(2))
+        .numDataNodes(dataNodeCount)
+        .storagesPerDatanode(diskCount)
+        .storageCapacities(new long[] {cap, cap})
+        .build();
+    cluster.waitActive();
+
+    DFSTestUtil.setFederatedConfiguration(cluster, conf);
+
+    final String fileName = "/tmp.txt";
+    final Path filePath = new Path(fileName);
+    long fileLen = blockCount * blockSize;
+
+
+    //Writing data only to one nameservice.
+    FileSystem fs = cluster.getFileSystem(0);
+    TestBalancer.createFile(cluster, filePath, fileLen, (short) 1,
+        0);
+    DFSTestUtil.waitReplication(fs, filePath, (short) 1);
+
+
+    GenericTestUtils.LogCapturer logCapturer = GenericTestUtils.LogCapturer
+        .captureLogs(DiskBalancer.LOG);
+
+    try {
+      DataMover dataMover = new DataMover(cluster, dataNodeIndex,
+          sourceDiskIndex, conf, blockSize, blockCount);
+      dataMover.moveDataToSourceDisk();
+      NodePlan plan = dataMover.generatePlan();
+      dataMover.executePlan(plan);
+      dataMover.verifyPlanExectionDone();
+      //Because here we have one nameservice empty, don't check
+      // blockPoolCount.
+      dataMover.verifyAllVolumesHaveData(false);
+    } finally {
+      Assert.assertTrue(logCapturer.getOutput().contains("There are no " +
+          "blocks in the blockPool"));
+      cluster.shutdown();
+    }
+
+  }
+
   @Test
   public void testBalanceDataBetweenMultiplePairsOfVolumes()
       throws Exception {
@@ -255,7 +315,7 @@ public class TestDiskBalancer {
 
       dataMover.executePlan(plan);
       dataMover.verifyPlanExectionDone();
-      dataMover.verifyAllVolumesHaveData();
+      dataMover.verifyAllVolumesHaveData(true);
       dataMover.verifyTolerance(plan, 0, sourceDiskIndex, 10);
     } finally {
       cluster.shutdown();
@@ -296,7 +356,7 @@ public class TestDiskBalancer {
       dataMover.moveDataToSourceDisk();
       NodePlan plan = dataMover.generatePlan();
       dataMover.executePlanDuringDiskRemove(plan);
-      dataMover.verifyAllVolumesHaveData();
+      dataMover.verifyAllVolumesHaveData(true);
       dataMover.verifyTolerance(plan, 0, sourceDiskIndex, 10);
     } catch (Exception e) {
       Assert.fail("Unexpected exception: " + e);
@@ -651,14 +711,15 @@ public class TestDiskBalancer {
     /**
      * Once diskBalancer is run, all volumes mush has some data.
      */
-    public void verifyAllVolumesHaveData() throws IOException {
+    public void verifyAllVolumesHaveData(boolean checkblockPoolCount) throws
+        IOException {
       node = cluster.getDataNodes().get(dataNodeIndex);
       try (FsDatasetSpi.FsVolumeReferences refs =
                node.getFSDataset().getFsVolumeReferences()) {
         for (FsVolumeSpi volume : refs) {
-          assertTrue(DiskBalancerTestUtil.getBlockCount(volume, true) > 0);
+          assertTrue(DiskBalancerTestUtil.getBlockCount(volume, checkblockPoolCount) > 0);
           LOG.info("{} : Block Count : {}", refs, DiskBalancerTestUtil
-              .getBlockCount(volume, true));
+              .getBlockCount(volume, checkblockPoolCount));
         }
       }
     }