siddhantsangwan commented on a change in pull request #2230:
URL: https://github.com/apache/ozone/pull/2230#discussion_r629901382
##########
File path:
hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/ContainerBalancer.java
##########
@@ -59,74 +80,305 @@ public ContainerBalancer(
this.ozoneConfiguration = ozoneConfiguration;
this.balancerRunning = false;
this.config = new ContainerBalancerConfiguration();
+ this.metrics = new ContainerBalancerMetrics();
}
/**
- * Start ContainerBalancer. Current implementation is incomplete.
+ * Starts ContainerBalancer. Current implementation is incomplete.
*
* @param balancerConfiguration Configuration values.
*/
public void start(ContainerBalancerConfiguration balancerConfiguration) {
+ if (balancerRunning) {
+ LOG.info("Container Balancer is already running.");
+ throw new RuntimeException();
+ }
this.balancerRunning = true;
-
ozoneConfiguration = new OzoneConfiguration();
- // initialise configs
this.config = balancerConfiguration;
this.threshold = config.getThreshold();
- this.maxDatanodesToBalance =
- config.getMaxDatanodesToBalance();
+ this.maxDatanodesToBalance = config.getMaxDatanodesToBalance();
this.maxSizeToMove = config.getMaxSizeToMove();
+ this.clusterCapacity = 0L;
+ this.clusterUsed = 0L;
+ this.clusterRemaining = 0L;
+
+ this.overUtilizedNodes = new ArrayList<>();
+ this.underUtilizedNodes = new ArrayList<>();
+ this.aboveAverageUtilizedNodes = new ArrayList<>();
+ this.belowAverageUtilizedNodes = new ArrayList<>();
+ this.sourceNodes = new ArrayList<>();
+
LOG.info("Starting Container Balancer...");
+ LOG.info(toString());
+
+ balance();
+ }
- // sorted list in order from most to least used
- List<DatanodeUsageInfo> nodes = nodeManager.
- getMostOrLeastUsedDatanodes(true);
- double avgUtilisation = calculateAvgUtilisation(nodes);
+ /**
+ * Balances the cluster.
+ */
+ private void balance() {
+ boolean initialized = initializeIteration();
+ }
+
+ /**
+ * Initializes an iteration during balancing. Recognizes over, under,
+ * below-average,and under-average utilizes nodes. Decides whether
+ * balancing needs to continue or should be stopped.
+ */
+ private boolean initializeIteration() {
+ List<DatanodeUsageInfo> nodes;
+ try {
+ // sorted list in order from most to least used
+ nodes = nodeManager.getMostOrLeastUsedDatanodes(true);
+ } catch (NullPointerException e) {
+ LOG.error("Container Balancer could not retrieve nodes from Node " +
+ "Manager.", e);
+ stop();
+ return false;
+ }
+
+ clusterAvgUtilisation = calculateAvgUtilization(nodes);
+ LOG.info("Average utilization of the cluster is {}",
clusterAvgUtilisation);
// under utilized nodes have utilization(that is, used / capacity) less
// than lower limit
- double lowerLimit = avgUtilisation - threshold;
+ double lowerLimit = clusterAvgUtilisation - threshold;
// over utilized nodes have utilization(that is, used / capacity) greater
// than upper limit
- double upperLimit = avgUtilisation + threshold;
+ double upperLimit = clusterAvgUtilisation + threshold;
+
LOG.info("Lower limit for utilization is {}", lowerLimit);
LOG.info("Upper limit for utilization is {}", upperLimit);
- // find over utilised(source) and under utilised(target) nodes
- sourceNodes = new ArrayList<>();
- targetNodes = new ArrayList<>();
-// for (DatanodeUsageInfo node : nodes) {
-// SCMNodeStat stat = node.getScmNodeStat();
-// double utilization = stat.getScmUsed().get().doubleValue() /
-// stat.getCapacity().get().doubleValue();
-// if (utilization > upperLimit) {
-// sourceNodes.add(node);
-// } else if (utilization < lowerLimit || utilization < avgUtilisation) {
-// targetNodes.add(node);
-// }
-// }
- }
-
- // calculate the average datanode utilisation across the cluster
- private double calculateAvgUtilisation(List<DatanodeUsageInfo> nodes) {
+ long numDatanodesToBalance = 0L;
+ double overLoadedBytes = 0D, underLoadedBytes = 0D;
+
+ // find over and under utilized nodes
+ for (DatanodeUsageInfo node : nodes) {
+ double utilization = calculateUtilization(node);
+ if (utilization > clusterAvgUtilisation) {
+ if (utilization > upperLimit) {
+ overUtilizedNodes.add(node);
+ numDatanodesToBalance += 1;
+
+ // amount of bytes greater than upper limit in this node
+ overLoadedBytes +=
+ ratioToBytes(node.getScmNodeStat().getCapacity().get(),
+ utilization) -
+ ratioToBytes(node.getScmNodeStat().getCapacity().get(),
+ upperLimit);
+ } else {
+ aboveAverageUtilizedNodes.add(node);
+ }
+ } else if (utilization < clusterAvgUtilisation) {
+ if (utilization < lowerLimit) {
+ underUtilizedNodes.add(node);
+ numDatanodesToBalance += 1;
+
+ // amount of bytes lesser than lower limit in this node
+ underLoadedBytes +=
+ ratioToBytes(node.getScmNodeStat().getCapacity().get(),
+ lowerLimit) -
+ ratioToBytes(node.getScmNodeStat().getCapacity().get(),
+ utilization);
+ } else {
+ belowAverageUtilizedNodes.add(node);
+ }
+ }
+ }
+
+ Collections.reverse(underUtilizedNodes);
+ Collections.reverse(belowAverageUtilizedNodes);
+
+ long numDatanodesBalanced = 0;
+ // count number of nodes that were balanced in previous iteration
+ for (DatanodeUsageInfo node : sourceNodes) {
+ if (!containsNode(overUtilizedNodes, node) &&
+ !containsNode(underUtilizedNodes, node)) {
+ numDatanodesBalanced += 1;
+ }
+ }
+ metrics.setNumDatanodesBalanced(new LongMetric(numDatanodesBalanced));
+ sourceNodes = new ArrayList<>(
+ overUtilizedNodes.size() + underUtilizedNodes.size());
+
+ if (numDatanodesBalanced + numDatanodesToBalance > maxDatanodesToBalance) {
+ LOG.info("Approaching Max Datanodes To Balance limit in Container " +
+ "Balancer. Stopping Balancer.");
+ stop();
+ return false;
+ } else {
+ sourceNodes.addAll(overUtilizedNodes);
+ sourceNodes.addAll(underUtilizedNodes);
Review comment:
Yes. However, the meaning of source nodes might change according to the
algorithm for moving containers. The term will be definite once the exact
algorithm is final.
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