HDFS-12299. Race Between update pipeline and DN Re-Registration. Contributed by Brahma Reddy Battula.

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java

@@ -1579,7 +1579,8 @@ class DataStreamer extends Daemon {
   }
 
   /** update pipeline at the namenode */
-  private void updatePipeline(long newGS) throws IOException {
+  @VisibleForTesting
+  void updatePipeline(long newGS) throws IOException {
     final ExtendedBlock oldBlock = block.getCurrentBlock();
     // the new GS has been propagated to all DN, it should be ok to update the
     // local block state

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

@@ -84,7 +84,7 @@ public class BlockUnderConstructionFeature {
     for(int i = 0; i < targets.length; i++) {
       // Only store non-null DatanodeStorageInfo.
       if (targets[i] != null) {
-        replicas[i] = new ReplicaUnderConstruction(block,
+        replicas[offset++] = new ReplicaUnderConstruction(block,
             targets[i], ReplicaState.RBW);
       }
     }

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

@@ -38,6 +38,9 @@ import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.BlockWrite;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
+import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.BlockUCState;
 import org.apache.hadoop.hdfs.server.datanode.DataNode;
 import org.apache.hadoop.hdfs.server.datanode.DataNodeFaultInjector;
@@ -706,4 +709,51 @@ public class TestClientProtocolForPipelineRecovery {
       cluster.shutdown();
     }
   }
+
+  @Test
+  public void testUpdatePipeLineAfterDNReg()throws Exception {
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = null;
+    try {
+      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(2).build();
+      cluster.waitActive();
+      FileSystem fileSys = cluster.getFileSystem();
+
+      Path file = new Path("/testUpdatePipeLineAfterDNReg");
+      FSDataOutputStream out = fileSys.create(file);
+      out.write(1);
+      out.hflush();
+      //Get the First DN and disable the heartbeats and then put in Deadstate
+      DFSOutputStream dfsOut = (DFSOutputStream) out.getWrappedStream();
+      DatanodeInfo[] pipeline = dfsOut.getPipeline();
+      DataNode dn1 = cluster.getDataNode(pipeline[0].getIpcPort());
+      dn1.setHeartbeatsDisabledForTests(true);
+      DatanodeDescriptor dn1Desc = cluster.getNamesystem(0).getBlockManager()
+          .getDatanodeManager().getDatanode(dn1.getDatanodeId());
+      cluster.setDataNodeDead(dn1Desc);
+      //Re-register the DeadNode
+      DatanodeProtocolClientSideTranslatorPB dnp =
+          new DatanodeProtocolClientSideTranslatorPB(
+          cluster.getNameNode().getNameNodeAddress(), conf);
+      dnp.registerDatanode(
+          dn1.getDNRegistrationForBP(cluster.getNamesystem().getBlockPoolId()));
+      DFSOutputStream dfsO = (DFSOutputStream) out.getWrappedStream();
+      String clientName = ((DistributedFileSystem) fileSys).getClient()
+          .getClientName();
+      NamenodeProtocols namenode = cluster.getNameNodeRpc();
+      //Update the genstamp and call updatepipeline
+      LocatedBlock newBlock = namenode
+          .updateBlockForPipeline(dfsO.getBlock(), clientName);
+      dfsO.getStreamer()
+          .updatePipeline(newBlock.getBlock().getGenerationStamp());
+      newBlock = namenode.updateBlockForPipeline(dfsO.getBlock(), clientName);
+      //Should not throw any error Pipeline should be success
+      dfsO.getStreamer()
+          .updatePipeline(newBlock.getBlock().getGenerationStamp());
+    } finally {
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
 }