HDFS-9393. After choosing favored nodes, choosing nodes for remaining replicas should go through BlockPlacementPolicy (Contributed by J.Andreina)

Author: vinayakumarb

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

@@ -2519,6 +2519,10 @@ Release 2.8.0 - UNRELEASED
     HDFS-9571. Fix ASF Licence warnings in Jenkins reports
     (Brahma Reddy Battula via cnauroth)
 
+    HDFS-9393. After choosing favored nodes, choosing nodes for remaining
+    replicas should go through BlockPlacementPolicy
+    (J.Andreina via vinayakumarb)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -147,11 +147,18 @@ DatanodeStorageInfo[] chooseTarget(String src,
           avoidStaleNodes, storageTypes);
 
       if (results.size() < numOfReplicas) {
-        // Not enough favored nodes, choose other nodes.
+        // Not enough favored nodes, choose other nodes, based on block
+        // placement policy (HDFS-9393).
         numOfReplicas -= results.size();
-        DatanodeStorageInfo[] remainingTargets = 
-            chooseTarget(src, numOfReplicas, writer, results,
-                false, favoriteAndExcludedNodes, blocksize, storagePolicy);
+        for (DatanodeStorageInfo storage : results) {
+          // add localMachine and related nodes to favoriteAndExcludedNodes
+          addToExcludedNodes(storage.getDatanodeDescriptor(),
+              favoriteAndExcludedNodes);
+        }
+        DatanodeStorageInfo[] remainingTargets =
+            chooseTarget(src, numOfReplicas, writer,
+                new ArrayList<DatanodeStorageInfo>(numOfReplicas), false,
+                favoriteAndExcludedNodes, blocksize, storagePolicy);
         for (int i = 0; i < remainingTargets.length; i++) {
           results.add(remainingTargets[i]);
         }

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

@@ -1464,4 +1464,44 @@ public void testupdateNeededReplicationsDoesNotCauseSkippedReplication()
     chosenBlocks = underReplicatedBlocks.chooseUnderReplicatedBlocks(1);
     assertTheChosenBlocks(chosenBlocks, 1, 0, 0, 0, 0);
   }
+
+  /**
+   * In this testcase, passed 2 favored nodes dataNodes[0],dataNodes[1]
+   *
+   * Both favored nodes should be chosen as target for placing replication and
+   * then should fall into BlockPlacement policy for choosing remaining targets
+   * ie. third target as local writer rack , forth target on remote rack and
+   * fifth on same rack as second.
+   *
+   * @throws Exception
+   */
+  @Test
+  public void testChooseExcessReplicaApartFromFavoredNodes() throws Exception {
+    DatanodeStorageInfo[] targets;
+    List<DatanodeDescriptor> expectedTargets =
+        new ArrayList<DatanodeDescriptor>();
+    expectedTargets.add(dataNodes[0]);
+    expectedTargets.add(dataNodes[1]);
+    expectedTargets.add(dataNodes[2]);
+    expectedTargets.add(dataNodes[4]);
+    expectedTargets.add(dataNodes[5]);
+    List<DatanodeDescriptor> favouredNodes =
+        new ArrayList<DatanodeDescriptor>();
+    favouredNodes.add(dataNodes[0]);
+    favouredNodes.add(dataNodes[1]);
+    targets = chooseTarget(5, dataNodes[2], null, favouredNodes);
+    assertEquals(targets.length, 5);
+    for (int i = 0; i < targets.length; i++) {
+      assertTrue("Target should be a part of Expected Targets",
+          expectedTargets.contains(targets[i].getDatanodeDescriptor()));
+    }
+  }
+
+  private DatanodeStorageInfo[] chooseTarget(int numOfReplicas,
+      DatanodeDescriptor writer, Set<Node> excludedNodes,
+      List<DatanodeDescriptor> favoredNodes) {
+    return replicator.chooseTarget(filename, numOfReplicas, writer,
+        excludedNodes, BLOCK_SIZE, favoredNodes,
+        TestBlockStoragePolicy.DEFAULT_STORAGE_POLICY);
+  }
 }

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

@@ -781,4 +781,36 @@ public void testChooseFavoredNodesNodeGroup() throws Exception {
     assertTrue("2nd Replica is incorrect",
       expectedTargets.contains(targets[1].getDatanodeDescriptor()));
   }
+
+  /**
+   * In this testcase, passed 3 favored nodes
+   * dataNodes[0],dataNodes[1],dataNodes[2]
+   *
+   * Favored nodes on different nodegroup should be selected. Remaining replica
+   * should go through BlockPlacementPolicy.
+   *
+   * @throws Exception
+   */
+  @Test
+  public void testChooseRemainingReplicasApartFromFavoredNodes()
+      throws Exception {
+    DatanodeStorageInfo[] targets;
+    List<DatanodeDescriptor> expectedTargets =
+        new ArrayList<DatanodeDescriptor>();
+    expectedTargets.add(dataNodes[0]);
+    expectedTargets.add(dataNodes[2]);
+    expectedTargets.add(dataNodes[3]);
+    expectedTargets.add(dataNodes[6]);
+    expectedTargets.add(dataNodes[7]);
+    List<DatanodeDescriptor> favouredNodes =
+        new ArrayList<DatanodeDescriptor>();
+    favouredNodes.add(dataNodes[0]);
+    favouredNodes.add(dataNodes[1]);
+    favouredNodes.add(dataNodes[2]);
+    targets = chooseTarget(3, dataNodes[3], null, favouredNodes);
+    for (int i = 0; i < targets.length; i++) {
+      assertTrue("Target should be a part of Expected Targets",
+          expectedTargets.contains(targets[i].getDatanodeDescriptor()));
+    }
+  }
 }