HDFS-7596. NameNode should prune dead storages from storageMap. Contributed by Arpit Agarwal.

(cherry picked from commit ef3c3a832c2f0c1e5ccdda2ff8ef84902912955f)
(cherry picked from commit 75e4e55e12b2faa521af7c23fddcba06a9ce661d)
(cherry picked from commit cc637d6ece64dfeb89e78c7e9766836149e098be)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -19,6 +19,9 @@ Release 2.6.1 - UNRELEASED
 
     HDFS-7182. JMX metrics aren't accessible when NN is busy. (Ming Ma via jing9)
 
+    HDFS-7596. NameNode should prune dead storages from storageMap.
+    (Arpit Agarwal via cnauroth)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeDescriptor.java

@@ -418,6 +418,46 @@ public class DatanodeDescriptor extends DatanodeInfo {
     if (checkFailedStorages) {
       updateFailedStorage(failedStorageInfos);
     }
+
+    if (storageMap.size() != reports.length) {
+      pruneStorageMap(reports);
+    }
+  }
+
+  /**
+   * Remove stale storages from storageMap. We must not remove any storages
+   * as long as they have associated block replicas.
+   */
+  private void pruneStorageMap(final StorageReport[] reports) {
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("Number of storages reported in heartbeat=" + reports.length +
+                    "; Number of storages in storageMap=" + storageMap.size());
+    }
+
+    HashMap<String, DatanodeStorageInfo> excessStorages;
+
+    synchronized (storageMap) {
+      // Init excessStorages with all known storages.
+      excessStorages = new HashMap<String, DatanodeStorageInfo>(storageMap);
+
+      // Remove storages that the DN reported in the heartbeat.
+      for (final StorageReport report : reports) {
+        excessStorages.remove(report.getStorage().getStorageID());
+      }
+
+      // For each remaining storage, remove it if there are no associated
+      // blocks.
+      for (final DatanodeStorageInfo storageInfo : excessStorages.values()) {
+        if (storageInfo.numBlocks() == 0) {
+          storageMap.remove(storageInfo.getStorageID());
+          LOG.info("Removed storage " + storageInfo + " from DataNode" + this);
+        } else if (LOG.isDebugEnabled()) {
+          // This can occur until all block reports are received.
+          LOG.debug("Deferring removal of stale storage " + storageInfo +
+                        " with " + storageInfo.numBlocks() + " blocks");
+        }
+      }
+    }
   }
 
   private void updateFailedStorage(
@@ -749,8 +789,6 @@ public class DatanodeDescriptor extends DatanodeInfo {
         // For backwards compatibility, make sure that the type and
         // state are updated. Some reports from older datanodes do
         // not include these fields so we may have assumed defaults.
-        // This check can be removed in the next major release after
-        // 2.4.
         storage.updateFromStorage(s);
         storageMap.put(storage.getStorageID(), storage);
       }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java

@@ -573,11 +573,13 @@ public class TestBlockManager {
     reset(node);
     bm.getDatanodeManager().registerDatanode(nodeReg);
     verify(node).updateRegInfo(nodeReg);
-    assertEquals(0, ds.getBlockReportCount()); // ready for report again
     // send block report, should be processed after restart
     reset(node);
     bm.processReport(node, new DatanodeStorage(ds.getStorageID()),
-        new BlockListAsLongs(null, null));
+                     new BlockListAsLongs(null, null));
+    // Reinitialize as registration with empty storage list pruned
+    // node.storageMap.
+    ds = node.getStorageInfos()[0];
     assertEquals(1, ds.getBlockReportCount());
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestNameNodePrunesMissingStorages.java

@@ -0,0 +1,121 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hdfs.server.blockmanagement;
+
+import org.apache.commons.lang.ArrayUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.commons.math3.stat.inference.TestUtils;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSTestUtil;
+import org.apache.hadoop.hdfs.HdfsConfiguration;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.server.datanode.DataNode;
+import org.apache.hadoop.hdfs.server.datanode.DataNodeTestUtils;
+import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
+import org.apache.hadoop.hdfs.server.protocol.StorageReport;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+
+public class TestNameNodePrunesMissingStorages {
+  static final Log LOG = LogFactory.getLog(TestNameNodePrunesMissingStorages.class);
+
+
+  private static void runTest(final String testCaseName,
+                              final boolean createFiles,
+                              final int numInitialStorages,
+                              final int expectedStoragesAfterTest) throws IOException {
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = null;
+
+    try {
+      cluster = new MiniDFSCluster
+          .Builder(conf)
+          .numDataNodes(1)
+          .storagesPerDatanode(numInitialStorages)
+          .build();
+      cluster.waitActive();
+
+      final DataNode dn0 = cluster.getDataNodes().get(0);
+
+      // Ensure NN knows about the storage.
+      final DatanodeID dnId = dn0.getDatanodeId();
+      final DatanodeDescriptor dnDescriptor =
+          cluster.getNamesystem().getBlockManager().getDatanodeManager().getDatanode(dnId);
+      assertThat(dnDescriptor.getStorageInfos().length, is(numInitialStorages));
+
+      final String bpid = cluster.getNamesystem().getBlockPoolId();
+      final DatanodeRegistration dnReg = dn0.getDNRegistrationForBP(bpid);
+      DataNodeTestUtils.triggerBlockReport(dn0);
+
+      if (createFiles) {
+        final Path path = new Path("/", testCaseName);
+        DFSTestUtil.createFile(
+            cluster.getFileSystem(), path, 1024, (short) 1, 0x1BAD5EED);
+        DataNodeTestUtils.triggerBlockReport(dn0);
+      }
+
+      // Generate a fake StorageReport that is missing one storage.
+      final StorageReport reports[] =
+          dn0.getFSDataset().getStorageReports(bpid);
+      final StorageReport prunedReports[] = new StorageReport[numInitialStorages - 1];
+      System.arraycopy(reports, 0, prunedReports, 0, prunedReports.length);
+
+      // Stop the DataNode and send fake heartbeat with missing storage.
+      cluster.stopDataNode(0);
+      cluster.getNameNodeRpc().sendHeartbeat(dnReg, prunedReports, 0L, 0L, 0, 0, 0);
+
+      // Check that the missing storage was pruned.
+      assertThat(dnDescriptor.getStorageInfos().length, is(expectedStoragesAfterTest));
+    } finally {
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
+
+  /**
+   * Test that the NameNode prunes empty storage volumes that are no longer
+   * reported by the DataNode.
+   * @throws IOException
+   */
+  @Test (timeout=300000)
+  public void testUnusedStorageIsPruned() throws IOException {
+    // Run the test with 1 storage, after the text expect 0 storages.
+    runTest(GenericTestUtils.getMethodName(), false, 1, 0);
+  }
+
+  /**
+   * Verify that the NameNode does not prune storages with blocks.
+   * @throws IOException
+   */
+  @Test (timeout=300000)
+  public void testStorageWithBlocksIsNotPruned() throws IOException {
+    // Run the test with 1 storage, after the text still expect 1 storage.
+    runTest(GenericTestUtils.getMethodName(), true, 1, 1);
+  }
+}