HDFS-17328. DiskBalancer should not computeNodeDensity every time when addVolume.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/connectors/DBNameNodeConnector.java

@@ -133,7 +133,9 @@ private void getVolumeInfoFromStorageReports(DiskBalancerDataNode node,
       throws Exception {
     Preconditions.checkNotNull(node);
     Preconditions.checkNotNull(reports);
-    for (StorageReport report : reports) {
+    int len = reports.length;
+    for (int i = 0; i < len; i++) {
+      StorageReport report = reports[i];
       DatanodeStorage storage = report.getStorage();
       DiskBalancerVolume volume = new DiskBalancerVolume();
       volume.setCapacity(report.getCapacity());
@@ -153,8 +155,11 @@ private void getVolumeInfoFromStorageReports(DiskBalancerDataNode node,
           .READ_ONLY_SHARED) || report.isFailed());
       volume.setStorageType(storage.getStorageType().name());
       volume.setIsTransient(storage.getStorageType().isTransient());
-      node.addVolume(volume);
+      boolean needComputeDensity = false;
+      if (i == len - 1) {
+        needComputeDensity = true;
+      }
+      node.addVolume(volume, needComputeDensity);
     }
-
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerDataNode.java

@@ -238,6 +238,10 @@ public boolean isBalancingNeeded(double threshold) {
    * @param volume - volume
    */
   public void addVolume(DiskBalancerVolume volume) throws Exception {
+    addVolume(volume, false);
+  }
+
+  public void addVolume(DiskBalancerVolume volume, boolean computeDensity) throws Exception {
     Preconditions.checkNotNull(volume, "volume cannot be null");
     Preconditions.checkNotNull(volumeSets, "volume sets cannot be null");
     Preconditions
@@ -254,7 +258,9 @@ public void addVolume(DiskBalancerVolume volume) throws Exception {
     }
 
     vSet.addVolume(volume);
-    computeNodeDensity();
+    if (computeDensity) {
+      computeNodeDensity();
+    }
   }
 
   /**