HDFS-11295. Check storage remaining instead of node remaining in BlockPlacementPolicyDefault.chooseReplicaToDelete(). Contributed by Marton Elek.

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

@@ -968,7 +968,7 @@ public DatanodeStorageInfo chooseReplicaToDelete(
       }
 
       final DatanodeDescriptor node = storage.getDatanodeDescriptor();
-      long free = node.getRemaining();
+      long free = storage.getRemaining();
       long lastHeartbeat = node.getLastUpdateMonotonic();
       if (lastHeartbeat < oldestHeartbeat) {
         oldestHeartbeat = lastHeartbeat;

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

@@ -388,6 +388,11 @@ static DatanodeStorageInfo getDatanodeStorageInfo(
     return null;
   }
 
+  @VisibleForTesting
+  void setRemainingForTests(int remaining) {
+    this.remaining = remaining;
+  }
+
   static enum AddBlockResult {
     ADDED, REPLACED, ALREADY_EXIST
   }

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

@@ -950,24 +950,31 @@ public void testChooseReplicaToDelete() throws Exception {
     List<DatanodeStorageInfo> replicaList = new ArrayList<>();
     final Map<String, List<DatanodeStorageInfo>> rackMap
         = new HashMap<String, List<DatanodeStorageInfo>>();
-    
+
-    dataNodes[0].setRemaining(4*1024*1024);
+    storages[0].setRemainingForTests(4*1024*1024);
+    dataNodes[0].setRemaining(calculateRemaining(dataNodes[0]));
     replicaList.add(storages[0]);
-    
+
-    dataNodes[1].setRemaining(3*1024*1024);
+    storages[1].setRemainingForTests(3*1024*1024);
+    dataNodes[1].setRemaining(calculateRemaining(dataNodes[1]));
     replicaList.add(storages[1]);
-    
+
-    dataNodes[2].setRemaining(2*1024*1024);
+    storages[2].setRemainingForTests(2*1024*1024);
+    dataNodes[2].setRemaining(calculateRemaining(dataNodes[2]));
     replicaList.add(storages[2]);
-    
+
-    dataNodes[5].setRemaining(1*1024*1024);
+    //Even if this node has the most space, because the storage[5] has
+    //the lowest it should be chosen in case of block delete.
+    storages[4].setRemainingForTests(100 * 1024 * 1024);
+    storages[5].setRemainingForTests(512 * 1024);
+    dataNodes[5].setRemaining(calculateRemaining(dataNodes[5]));
     replicaList.add(storages[5]);
-    
+
     // Refresh the last update time for all the datanodes
     for (int i = 0; i < dataNodes.length; i++) {
       DFSTestUtil.resetLastUpdatesWithOffset(dataNodes[i], 0);
     }
-    
+
     List<DatanodeStorageInfo> first = new ArrayList<>();
     List<DatanodeStorageInfo> second = new ArrayList<>();
     replicator.splitNodesWithRack(replicaList, replicaList, rackMap, first,
@@ -999,6 +1006,14 @@ public void testChooseReplicaToDelete() throws Exception {
     assertEquals(chosen, storages[1]);
   }
 
+  private long calculateRemaining(DatanodeDescriptor dataNode) {
+    long sum = 0;
+    for (DatanodeStorageInfo storageInfo: dataNode.getStorageInfos()){
+      sum += storageInfo.getRemaining();
+    }
+    return sum;
+  }
+
   @Test
   public void testChooseReplicasToDelete() throws Exception {
     Collection<DatanodeStorageInfo> nonExcess = new ArrayList<>();

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

@@ -625,16 +625,21 @@ public void testRereplicate3() throws Exception {
   public void testChooseReplicaToDelete() throws Exception {
     List<DatanodeStorageInfo> replicaList = new ArrayList<>();
     final Map<String, List<DatanodeStorageInfo>> rackMap = new HashMap<>();
-    dataNodes[0].setRemaining(4*1024*1024);
+    storages[0].setRemainingForTests(4*1024*1024);
+    dataNodes[0].setRemaining(calculateRemaining(dataNodes[0]));
     replicaList.add(storages[0]);
 
-    dataNodes[1].setRemaining(3*1024*1024);
+    storages[1].setRemainingForTests(3*1024*1024);
+    dataNodes[1].setRemaining(calculateRemaining(dataNodes[1]));
     replicaList.add(storages[1]);
 
-    dataNodes[2].setRemaining(2*1024*1024);
+    storages[2].setRemainingForTests(2*1024*1024);
+    dataNodes[2].setRemaining(calculateRemaining(dataNodes[2]));
     replicaList.add(storages[2]);
 
-    dataNodes[5].setRemaining(1*1024*1024);
+    storages[4].setRemainingForTests(100 * 1024 * 1024);
+    storages[5].setRemainingForTests(512 * 1024);
+    dataNodes[5].setRemaining(calculateRemaining(dataNodes[5]));
     replicaList.add(storages[5]);
 
     List<DatanodeStorageInfo> first = new ArrayList<>();
@@ -671,7 +676,15 @@ public void testChooseReplicaToDelete() throws Exception {
         first, second, excessTypes, rackMap);
     assertEquals(chosen, storages[5]);
   }
-  
+
+  private long calculateRemaining(DatanodeDescriptor dataNode) {
+    long sum = 0;
+    for (DatanodeStorageInfo storageInfo: dataNode.getStorageInfos()){
+      sum += storageInfo.getRemaining();
+    }
+    return sum;
+  }
+
   /**
    * Test replica placement policy in case of boundary topology.
    * Rack 2 has only 1 node group & can't be placed with two replicas