[GitHub] [ozone] JacksonYao287 commented on a change in pull request #2808: HDDS-5517. Support multiple container moves from a source datanode in one balance iteration

[GitBox <gi...@apache.org>]

JacksonYao287 commented on a change in pull request #2808:
URL: https://github.com/apache/ozone/pull/2808#discussion_r748058383



##########
File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/ContainerBalancer.java
##########
@@ -518,6 +485,27 @@ private ContainerMoveSelection matchSourceWithTarget(
       }
       return null;
     }
+
+    //if the utilization of the source data node becomes lower than lowerLimit
+    //after the container is moved out , then the container can not be
+    // a candidate one, and we should remove it from the candidateContainers.
+    candidateContainers.removeIf(c -> {
+      ContainerInfo cInfo;
+      try {
+        cInfo = containerManager.getContainer(c);
+      } catch (ContainerNotFoundException e) {
+        LOG.warn("Could not find container {} when " +
+            "be matched with a move target", c);
+        //remove this not found container
+        return true;
+      }
+      Long totalLeavingSize = sizeLeavingNode.get(source) +
+          cInfo.getUsedBytes();
+      return Double.compare(nodeManager.getUsageInfo(source)
+        .calculateUtilization(totalLeavingSize), lowerLimit) < 0 ||
+          totalLeavingSize > config.getMaxSizeLeavingSource();
+    });

Review comment:
       thanks for pointing out this,  will fix it!
   

##########
File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/ContainerBalancer.java
##########
@@ -262,20 +261,17 @@ private boolean initializeIteration() {
           clusterAvgUtilisation);
     }
 
-    // under utilized nodes have utilization(that is, used / capacity) less
-    // than lower limit

Review comment:
       sorry for this, i did not meant to remove this comment, i will add it back

##########
File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/SourceDataNodeSelectionCriteria.java
##########
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership.  The ASF
+ * licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package org.apache.hadoop.hdds.scm.container.balancer;
+
+import org.apache.hadoop.hdds.protocol.DatanodeDetails;
+import org.apache.hadoop.hdds.scm.node.DatanodeUsageInfo;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * The selection criteria for selecting source datanodes , the containers of
+ * which will be moved out.
+ */
+public class SourceDataNodeSelectionCriteria {
+  private static final Logger LOG =
+      LoggerFactory.getLogger(SourceDataNodeSelectionCriteria.class);
+  private Map<DatanodeDetails, Long> sizeLeavingNode;
+  private List<DatanodeUsageInfo> overUtilizedNodes;
+
+  public SourceDataNodeSelectionCriteria(
+      List<DatanodeUsageInfo> overUtilizedNodes,
+      Map<DatanodeDetails, Long> sizeLeavingNode) {
+    this.sizeLeavingNode = sizeLeavingNode;
+    this.overUtilizedNodes = overUtilizedNodes;
+  }
+
+  public DatanodeDetails getNextCandidateSourceDataNode() {
+    if (overUtilizedNodes.isEmpty()) {
+      LOG.info("no more candidate data node");
+      return null;
+    }
+    //TODO：use a more quick data structure, which will hava a
+    // better performance when changing or deleting one element at once
+    overUtilizedNodes.sort((a, b) -> {
+      double currentUsageOfA = a.calculateUtilization(
+          sizeLeavingNode.get(a.getDatanodeDetails()));
+      double currentUsageOfB = b.calculateUtilization(
+          sizeLeavingNode.get(b.getDatanodeDetails()));
+      //in descending order
+      return Double.compare(currentUsageOfB, currentUsageOfA);
+    });

Review comment:
       >I think we want to sort by reducing the used space (subtracting sizeLeavingNode) and then calculating utilization.
   
   yes , that is correct. `getNextCandidateSourceDataNode` always try to return a source data node with the highest usage. thanks very much for pointing out this mistake!

##########
File path: hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/ContainerBalancer.java
##########
@@ -708,8 +696,8 @@ boolean canSizeEnterTarget(DatanodeDetails target, long size) {
       //2 current usage of target datanode plus sizeEnteringAfterMove
       // is smaller than or equal to upperLimit
       return sizeEnteringAfterMove <= config.getMaxSizeEnteringTarget() &&
-           nodeManager.getUsageInfo(target)
-               .calculateUtilization(sizeEnteringAfterMove) <= upperLimit;
+           Double.compare(nodeManager.getUsageInfo(target)
+               .calculateUtilization(sizeEnteringAfterMove), upperLimit) < 1;

Review comment:
       the return type of `Double.compare` is int , so `< 1`  is equal to `<= 0` here. but `<=0` seems more clear, will fix this, thanks.




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