HDFS-14849. Erasure Coding: the internal block is replicated many times when datanode is decommissioning. Contributed by HuangTao.

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

@@ -2359,11 +2359,13 @@ public class BlockManager implements BlockStatsMXBean {
       if (isStriped) {
         blockIndex = ((BlockInfoStriped) block)
             .getStorageBlockIndex(storage);
-        if (!bitSet.get(blockIndex)) {
-          bitSet.set(blockIndex);
-        } else if (state == StoredReplicaState.LIVE) {
-          numReplicas.subtract(StoredReplicaState.LIVE, 1);
-          numReplicas.add(StoredReplicaState.REDUNDANT, 1);
+        if (state == StoredReplicaState.LIVE) {
+          if (!bitSet.get(blockIndex)) {
+            bitSet.set(blockIndex);
+          } else {
+            numReplicas.subtract(StoredReplicaState.LIVE, 1);
+            numReplicas.add(StoredReplicaState.REDUNDANT, 1);
+          }
         }
       }
 

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlockMissingException.java

@@ -19,7 +19,6 @@ package org.apache.hadoop.hdfs;
 
 import static org.junit.Assert.assertTrue;
 
-import java.io.File;
 import java.io.IOException;
 
 import org.slf4j.Logger;
@@ -31,7 +30,6 @@ import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
-import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.junit.Test;
 

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

@@ -21,6 +21,7 @@ import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.LinkedListMultimap;
 import com.google.common.collect.Lists;
+import org.apache.hadoop.hdfs.protocol.SystemErasureCodingPolicies;
 import org.slf4j.LoggerFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CreateFlag;
@@ -748,6 +749,63 @@ public class TestBlockManager {
             numReplicas.redundantInternalBlocks());
   }
 
+  @Test
+  public void testChooseSrcDNWithDupECInDecommissioningNode() throws Exception {
+    long blockId = -9223372036854775776L; // real ec block id
+    Block aBlock = new Block(blockId, 0, 0);
+    // RS-3-2 EC policy
+    ErasureCodingPolicy ecPolicy =
+        SystemErasureCodingPolicies.getPolicies().get(1);
+    // striped blockInfo
+    BlockInfoStriped aBlockInfoStriped = new BlockInfoStriped(aBlock, ecPolicy);
+    // ec storageInfo
+    DatanodeStorageInfo ds1 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage1", "1.1.1.1", "rack1", "host1");
+    DatanodeStorageInfo ds2 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage2", "2.2.2.2", "rack2", "host2");
+    DatanodeStorageInfo ds3 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage3", "3.3.3.3", "rack3", "host3");
+    DatanodeStorageInfo ds4 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage4", "4.4.4.4", "rack4", "host4");
+    DatanodeStorageInfo ds5 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage5", "5.5.5.5", "rack5", "host5");
+    DatanodeStorageInfo ds6 = DFSTestUtil.createDatanodeStorageInfo(
+        "storage6", "6.6.6.6", "rack6", "host6");
+
+    // link block with storage
+    aBlockInfoStriped.addStorage(ds1, aBlock);
+    aBlockInfoStriped.addStorage(ds2, new Block(blockId + 1, 0, 0));
+    aBlockInfoStriped.addStorage(ds3, new Block(blockId + 2, 0, 0));
+    aBlockInfoStriped.addStorage(ds4, new Block(blockId + 3, 0, 0));
+    aBlockInfoStriped.addStorage(ds5, new Block(blockId + 4, 0, 0));
+    // NOTE: duplicate block 0，this DN will replace the decommission ds1 DN
+    aBlockInfoStriped.addStorage(ds6, aBlock);
+
+    addEcBlockToBM(blockId, ecPolicy);
+    // decommission datanode where store block 0
+    ds1.getDatanodeDescriptor().startDecommission();
+
+    List<DatanodeDescriptor> containingNodes =
+        new LinkedList<DatanodeDescriptor>();
+    List<DatanodeStorageInfo> nodesContainingLiveReplicas =
+        new LinkedList<DatanodeStorageInfo>();
+    NumberReplicas numReplicas = new NumberReplicas();
+    List<Byte> liveBlockIndices = new ArrayList<>();
+
+    bm.chooseSourceDatanodes(
+        aBlockInfoStriped,
+        containingNodes,
+        nodesContainingLiveReplicas,
+        numReplicas, liveBlockIndices,
+        LowRedundancyBlocks.QUEUE_HIGHEST_PRIORITY);
+    assertEquals("There are 5 live replicas in " +
+            "[ds2, ds3, ds4, ds5, ds6] datanodes ",
+        5, numReplicas.liveReplicas());
+    assertEquals("The ds1 datanode is in decommissioning, " +
+            "so there is no redundant replica",
+        0, numReplicas.redundantInternalBlocks());
+  }
+
   @Test
   public void testFavorDecomUntilHardLimit() throws Exception {
     bm.maxReplicationStreams = 0;