HDFS-8988. Use LightWeightHashSet instead of LightWeightLinkedSet in BlockManager#excessReplicateMap. (yliu)

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

@@ -1512,6 +1512,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9221. HdfsServerConstants#ReplicaState#getState should avoid calling
     values() since it creates a temporary array. (Staffan Friberg via yliu)
 
+    HDFS-8988. Use LightWeightHashSet instead of LightWeightLinkedSet in
+    BlockManager#excessReplicateMap. (yliu)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

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

@@ -89,7 +89,6 @@ import org.apache.hadoop.hdfs.server.protocol.KeyUpdateCommand;
 import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.server.protocol.StorageReceivedDeletedBlocks;
 import org.apache.hadoop.hdfs.util.LightWeightHashSet;
-import org.apache.hadoop.hdfs.util.LightWeightLinkedSet;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
 
 import static org.apache.hadoop.hdfs.util.StripedBlockUtil.getInternalBlockLength;
@@ -219,7 +218,7 @@ public class BlockManager implements BlockStatsMXBean {
    * Maps a StorageID to the set of blocks that are "extra" for this
    * DataNode. We'll eventually remove these extras.
    */
-  public final Map<String, LightWeightLinkedSet<BlockInfo>> excessReplicateMap =
+  public final Map<String, LightWeightHashSet<BlockInfo>> excessReplicateMap =
     new HashMap<>();
 
   /**
@@ -1421,11 +1420,6 @@ public class BlockManager implements BlockStatsMXBean {
    */
   @VisibleForTesting
   int computeRecoveryWorkForBlocks(List<List<BlockInfo>> blocksToRecover) {
-    int requiredReplication, numEffectiveReplicas;
-    List<DatanodeDescriptor> containingNodes;
-    BlockCollection bc;
-    int additionalReplRequired;
-
     int scheduledWork = 0;
     List<BlockRecoveryWork> recovWork = new LinkedList<>();
 
@@ -1786,7 +1780,7 @@ public class BlockManager implements BlockStatsMXBean {
     Collection<DatanodeDescriptor> nodesCorrupt = corruptReplicas.getNodes(block);
     for (DatanodeStorageInfo storage : blocksMap.getStorages(block)) {
       final DatanodeDescriptor node = storage.getDatanodeDescriptor();
-      LightWeightLinkedSet<BlockInfo> excessBlocks =
+      LightWeightHashSet<BlockInfo> excessBlocks =
         excessReplicateMap.get(node.getDatanodeUuid());
       int countableReplica = storage.getState() == State.NORMAL ? 1 : 0;
       if ((nodesCorrupt != null) && (nodesCorrupt.contains(node)))
@@ -3090,7 +3084,7 @@ public class BlockManager implements BlockStatsMXBean {
         postponeBlock(block);
         return;
       }
-      LightWeightLinkedSet<BlockInfo> excessBlocks = excessReplicateMap.get(
+      LightWeightHashSet<BlockInfo> excessBlocks = excessReplicateMap.get(
           cur.getDatanodeUuid());
       if (excessBlocks == null || !excessBlocks.contains(block)) {
         if (!cur.isDecommissionInProgress() && !cur.isDecommissioned()) {
@@ -3297,10 +3291,10 @@ public class BlockManager implements BlockStatsMXBean {
 
   private void addToExcessReplicate(DatanodeInfo dn, BlockInfo storedBlock) {
     assert namesystem.hasWriteLock();
-    LightWeightLinkedSet<BlockInfo> excessBlocks = excessReplicateMap.get(
+    LightWeightHashSet<BlockInfo> excessBlocks = excessReplicateMap.get(
         dn.getDatanodeUuid());
     if (excessBlocks == null) {
-      excessBlocks = new LightWeightLinkedSet<>();
+      excessBlocks = new LightWeightHashSet<>();
       excessReplicateMap.put(dn.getDatanodeUuid(), excessBlocks);
     }
     if (excessBlocks.add(storedBlock)) {
@@ -3364,7 +3358,7 @@ public class BlockManager implements BlockStatsMXBean {
       // We've removed a block from a node, so it's definitely no longer
       // in "excess" there.
       //
-      LightWeightLinkedSet<BlockInfo> excessBlocks = excessReplicateMap.get(
+      LightWeightHashSet<BlockInfo> excessBlocks = excessReplicateMap.get(
           node.getDatanodeUuid());
       if (excessBlocks != null) {
         if (excessBlocks.remove(storedBlock)) {
@@ -3581,7 +3575,7 @@ public class BlockManager implements BlockStatsMXBean {
       } else if (node.isDecommissioned()) {
         decommissioned++;
       } else {
-        LightWeightLinkedSet<BlockInfo> blocksExcess = excessReplicateMap.get(
+        LightWeightHashSet<BlockInfo> blocksExcess = excessReplicateMap.get(
             node.getDatanodeUuid());
         if (blocksExcess != null && blocksExcess.contains(b)) {
           excess++;
@@ -3988,7 +3982,8 @@ public class BlockManager implements BlockStatsMXBean {
   private void removeFromExcessReplicateMap(Block block) {
     for (DatanodeStorageInfo info : blocksMap.getStorages(block)) {
       String uuid = info.getDatanodeDescriptor().getDatanodeUuid();
-      LightWeightLinkedSet<BlockInfo> excessReplicas = excessReplicateMap.get(uuid);
+      LightWeightHashSet<BlockInfo> excessReplicas =
+          excessReplicateMap.get(uuid);
       if (excessReplicas != null) {
         if (excessReplicas.remove(block)) {
           excessBlocksCount.decrementAndGet();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeFsck.java

@@ -74,7 +74,7 @@ import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeStorageInfo;
 import org.apache.hadoop.hdfs.server.blockmanagement.NumberReplicas;
 import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
-import org.apache.hadoop.hdfs.util.LightWeightLinkedSet;
+import org.apache.hadoop.hdfs.util.LightWeightHashSet;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.net.NetworkTopology;
 import org.apache.hadoop.net.NodeBase;
@@ -687,7 +687,7 @@ public class NamenodeFsck implements DataEncryptionKeyFactory {
                   .getStorageType()));
             }
             if (showReplicaDetails) {
-              LightWeightLinkedSet<BlockInfo> blocksExcess =
+              LightWeightHashSet<BlockInfo> blocksExcess =
                   bm.excessReplicateMap.get(dnDesc.getDatanodeUuid());
               Collection<DatanodeDescriptor> corruptReplicas =
                   bm.getCorruptReplicas(block.getLocalBlock());