HDFS-9445. Datanode may deadlock while handling a bad volume. Contributed by Walter Su.

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

@@ -2574,6 +2574,9 @@ Release 2.7.2 - UNRELEASED
     HDFS-9294. DFSClient deadlock when close file and failed to renew lease.
     (Brahma Reddy Battula via szetszwo)
 
+    HDFS-9445. Datanode may deadlock while handling a bad volume.
+    (Wlater Su via Kihwal)
+
 Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES

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

@@ -470,48 +470,67 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
    * Removes a set of volumes from FsDataset.
    * @param volumesToRemove a set of absolute root path of each volume.
    * @param clearFailure set true to clear failure information.
-   *
-   * DataNode should call this function before calling
-   * {@link DataStorage#removeVolumes(java.util.Collection)}.
    */
   @Override
-  public synchronized void removeVolumes(
-      Set<File> volumesToRemove, boolean clearFailure) {
+  public void removeVolumes(Set<File> volumesToRemove, boolean clearFailure) {
     // Make sure that all volumes are absolute path.
     for (File vol : volumesToRemove) {
       Preconditions.checkArgument(vol.isAbsolute(),
           String.format("%s is not absolute path.", vol.getPath()));
     }
-    for (int idx = 0; idx < dataStorage.getNumStorageDirs(); idx++) {
-      Storage.StorageDirectory sd = dataStorage.getStorageDir(idx);
-      final File absRoot = sd.getRoot().getAbsoluteFile();
-      if (volumesToRemove.contains(absRoot)) {
-        LOG.info("Removing " + absRoot + " from FsDataset.");
-
-        // Disable the volume from the service.
-        asyncDiskService.removeVolume(sd.getCurrentDir());
-        volumes.removeVolume(absRoot, clearFailure);
-
-        // Removed all replica information for the blocks on the volume. Unlike
-        // updating the volumeMap in addVolume(), this operation does not scan
-        // disks.
-        for (String bpid : volumeMap.getBlockPoolList()) {
-          for (Iterator<ReplicaInfo> it = volumeMap.replicas(bpid).iterator();
-               it.hasNext(); ) {
-            ReplicaInfo block = it.next();
-            final File absBasePath =
-                new File(block.getVolume().getBasePath()).getAbsoluteFile();
-            if (absBasePath.equals(absRoot)) {
-              invalidate(bpid, block);
-              it.remove();
+
+    Map<String, List<ReplicaInfo>> blkToInvalidate = new HashMap<>();
+    List<String> storageToRemove = new ArrayList<>();
+    synchronized (this) {
+      for (int idx = 0; idx < dataStorage.getNumStorageDirs(); idx++) {
+        Storage.StorageDirectory sd = dataStorage.getStorageDir(idx);
+        final File absRoot = sd.getRoot().getAbsoluteFile();
+        if (volumesToRemove.contains(absRoot)) {
+          LOG.info("Removing " + absRoot + " from FsDataset.");
+
+          // Disable the volume from the service.
+          asyncDiskService.removeVolume(sd.getCurrentDir());
+          volumes.removeVolume(absRoot, clearFailure);
+
+          // Removed all replica information for the blocks on the volume.
+          // Unlike updating the volumeMap in addVolume(), this operation does
+          // not scan disks.
+          for (String bpid : volumeMap.getBlockPoolList()) {
+            List<ReplicaInfo> blocks = new ArrayList<>();
+            for (Iterator<ReplicaInfo> it = volumeMap.replicas(bpid).iterator();
+                 it.hasNext(); ) {
+              ReplicaInfo block = it.next();
+              final File absBasePath =
+                  new File(block.getVolume().getBasePath()).getAbsoluteFile();
+              if (absBasePath.equals(absRoot)) {
+                blocks.add(block);
+                it.remove();
+              }
             }
+            blkToInvalidate.put(bpid, blocks);
           }
+
+          storageToRemove.add(sd.getStorageUuid());
         }
+      }
+      setupAsyncLazyPersistThreads();
+    }
 
-        storageMap.remove(sd.getStorageUuid());
+    // Call this outside the lock.
+    for (Map.Entry<String, List<ReplicaInfo>> entry :
+        blkToInvalidate.entrySet()) {
+      String bpid = entry.getKey();
+      List<ReplicaInfo> blocks = entry.getValue();
+      for (ReplicaInfo block : blocks) {
+        invalidate(bpid, block);
+      }
+    }
+
+    synchronized (this) {
+      for(String storageUuid : storageToRemove) {
+        storageMap.remove(storageUuid);
       }
     }
-    setupAsyncLazyPersistThreads();
   }
 
   private StorageType getStorageTypeFromLocations(
@@ -1931,15 +1950,11 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   public void invalidate(String bpid, ReplicaInfo block) {
     // If a DFSClient has the replica in its cache of short-circuit file
     // descriptors (and the client is using ShortCircuitShm), invalidate it.
-    // The short-circuit registry is null in the unit tests, because the
-    // datanode is mock object.
-    if (datanode.getShortCircuitRegistry() != null) {
-      datanode.getShortCircuitRegistry().processBlockInvalidation(
-          new ExtendedBlockId(block.getBlockId(), bpid));
+    datanode.getShortCircuitRegistry().processBlockInvalidation(
+        new ExtendedBlockId(block.getBlockId(), bpid));
 
-      // If the block is cached, start uncaching it.
-      cacheManager.uncacheBlock(bpid, block.getBlockId());
-    }
+    // If the block is cached, start uncaching it.
+    cacheManager.uncacheBlock(bpid, block.getBlockId());
 
     datanode.notifyNamenodeDeletedBlock(new ExtendedBlock(bpid, block),
         block.getStorageUuid());

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/TestFsDatasetImpl.java

@@ -39,6 +39,7 @@ import org.apache.hadoop.hdfs.server.datanode.DataStorage;
 import org.apache.hadoop.hdfs.server.datanode.FinalizedReplica;
 import org.apache.hadoop.hdfs.server.datanode.ReplicaHandler;
 import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo;
+import org.apache.hadoop.hdfs.server.datanode.ShortCircuitRegistry;
 import org.apache.hadoop.hdfs.server.datanode.StorageLocation;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeReference;
@@ -147,6 +148,9 @@ public class TestFsDatasetImpl {
     when(datanode.getDnConf()).thenReturn(dnConf);
     final BlockScanner disabledBlockScanner = new BlockScanner(datanode, conf);
     when(datanode.getBlockScanner()).thenReturn(disabledBlockScanner);
+    final ShortCircuitRegistry shortCircuitRegistry =
+        new ShortCircuitRegistry(conf);
+    when(datanode.getShortCircuitRegistry()).thenReturn(shortCircuitRegistry);
 
     createStorageDirs(storage, conf, NUM_INIT_VOLUMES);
     dataset = new FsDatasetImpl(datanode, storage, conf);