HDFS-5662. Can't decommission a DataNode due to file's replication factor larger than the rest of the cluster size. Contributed by Brandon Li

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1552131 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -839,6 +839,9 @@ Release 2.3.0 - UNRELEASED
     HDFS-5592. statechangeLog of completeFile should be logged only in case of success. 
     (Vinayakumar via umamahesh)
 
+    HDFS-5662. Can't decommission a DataNode due to file's replication factor
+    larger than the rest of the cluster size. (brandonli)
+
   OPTIMIZATIONS
 
   BUG FIXES

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

@@ -2893,6 +2893,7 @@ assert storedBlock.findDatanode(dn) < 0 : "Block " + block
    */
   boolean isReplicationInProgress(DatanodeDescriptor srcNode) {
     boolean status = false;
+    boolean firstReplicationLog = true;
     int underReplicatedBlocks = 0;
     int decommissionOnlyReplicas = 0;
     int underReplicatedInOpenFiles = 0;
@@ -2907,11 +2908,18 @@ assert storedBlock.findDatanode(dn) < 0 : "Block " + block
         int curExpectedReplicas = getReplication(block);
         if (isNeededReplication(block, curExpectedReplicas, curReplicas)) {
           if (curExpectedReplicas > curReplicas) {
-            //Log info about one block for this node which needs replication
+            // Log info about one block for this node which needs replication
             if (!status) {
               status = true;
+              if (firstReplicationLog) {
                 logBlockReplicationInfo(block, srcNode, num);
               }
+              // Allowing decommission as long as default replication is met
+              if (curReplicas >= defaultReplication) {
+                status = false;
+                firstReplicationLog = false;
+              }
+            }
             underReplicatedBlocks++;
             if ((curReplicas == 0) && (num.decommissionedReplicas() > 0)) {
               decommissionOnlyReplicas++;

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

@@ -336,6 +336,58 @@ public class TestDecommission {
     testDecommission(1, 6);
   }
   
+  /**
+   * Tests decommission with replicas on the target datanode cannot be migrated
+   * to other datanodes and satisfy the replication factor. Make sure the
+   * datanode won't get stuck in decommissioning state.
+   */
+  @Test(timeout = 360000)
+  public void testDecommission2() throws IOException {
+    LOG.info("Starting test testDecommission");
+    int numNamenodes = 1;
+    int numDatanodes = 4;
+    conf.setInt(DFSConfigKeys.DFS_REPLICATION_KEY, 3);
+    startCluster(numNamenodes, numDatanodes, conf);
+
+    ArrayList<ArrayList<DatanodeInfo>> namenodeDecomList = new ArrayList<ArrayList<DatanodeInfo>>(
+        numNamenodes);
+    namenodeDecomList.add(0, new ArrayList<DatanodeInfo>(numDatanodes));
+
+    Path file1 = new Path("testDecommission2.dat");
+    int replicas = 4;
+
+    // Start decommissioning one namenode at a time
+    ArrayList<DatanodeInfo> decommissionedNodes = namenodeDecomList.get(0);
+    FileSystem fileSys = cluster.getFileSystem(0);
+    FSNamesystem ns = cluster.getNamesystem(0);
+
+    writeFile(fileSys, file1, replicas);
+
+    int deadDecomissioned = ns.getNumDecomDeadDataNodes();
+    int liveDecomissioned = ns.getNumDecomLiveDataNodes();
+
+    // Decommission one node. Verify that node is decommissioned.
+    DatanodeInfo decomNode = decommissionNode(0, decommissionedNodes,
+        AdminStates.DECOMMISSIONED);
+    decommissionedNodes.add(decomNode);
+    assertEquals(deadDecomissioned, ns.getNumDecomDeadDataNodes());
+    assertEquals(liveDecomissioned + 1, ns.getNumDecomLiveDataNodes());
+
+    // Ensure decommissioned datanode is not automatically shutdown
+    DFSClient client = getDfsClient(cluster.getNameNode(0), conf);
+    assertEquals("All datanodes must be alive", numDatanodes,
+        client.datanodeReport(DatanodeReportType.LIVE).length);
+    assertNull(checkFile(fileSys, file1, replicas, decomNode.getXferAddr(),
+        numDatanodes));
+    cleanupFile(fileSys, file1);
+
+    // Restart the cluster and ensure recommissioned datanodes
+    // are allowed to register with the namenode
+    cluster.shutdown();
+    startCluster(1, 4, conf);
+    cluster.shutdown();
+  }
+  
   /**
    * Tests recommission for non federated cluster
    */
@@ -388,7 +440,20 @@ public class TestDecommission {
         DFSClient client = getDfsClient(cluster.getNameNode(i), conf);
         assertEquals("All datanodes must be alive", numDatanodes, 
             client.datanodeReport(DatanodeReportType.LIVE).length);
-        assertNull(checkFile(fileSys, file1, replicas, decomNode.getXferAddr(), numDatanodes));
+        // wait for the block to be replicated
+        int tries = 0;
+        while (tries++ < 20) {
+          try {
+            Thread.sleep(1000);
+            if (checkFile(fileSys, file1, replicas, decomNode.getXferAddr(),
+                numDatanodes) == null) {
+              break;
+            }
+          } catch (InterruptedException ie) {
+          }
+        }
+        assertTrue("Checked if block was replicated after decommission, tried "
+            + tries + " times.", tries < 20);
         cleanupFile(fileSys, file1);
       }
     }
@@ -429,12 +494,25 @@ public class TestDecommission {
       DFSClient client = getDfsClient(cluster.getNameNode(i), conf);
       assertEquals("All datanodes must be alive", numDatanodes, 
           client.datanodeReport(DatanodeReportType.LIVE).length);
-      assertNull(checkFile(fileSys, file1, replicas, decomNode.getXferAddr(), numDatanodes));
+      int tries =0;
+      // wait for the block to be replicated
+      while (tries++ < 20) {
+        try {
+          Thread.sleep(1000);
+          if (checkFile(fileSys, file1, replicas, decomNode.getXferAddr(),
+              numDatanodes) == null) {
+            break;
+          }
+        } catch (InterruptedException ie) {
+        }
+      }
+      assertTrue("Checked if block was replicated after decommission, tried "
+          + tries + " times.", tries < 20);
 
       // stop decommission and check if the new replicas are removed
       recomissionNode(decomNode);
       // wait for the block to be deleted
-      int tries = 0;
+      tries = 0;
       while (tries++ < 20) {
         try {
           Thread.sleep(1000);