lokeshj1703 commented on a change in pull request #3129:
URL: https://github.com/apache/ozone/pull/3129#discussion_r835138978
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File path:
hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/container/balancer/ContainerBalancer.java
##########
@@ -408,57 +410,77 @@ private IterationResult doIteration() {
new HashSet<>(potentialTargets.size());
moveSelectionToFutureMap = new HashMap<>(unBalancedNodes.size());
boolean isMoveGenerated = false;
- try {
- // match each overUtilized node with a target
- while (true) {
- if (!isBalancerRunning()) {
- return IterationResult.ITERATION_INTERRUPTED;
- }
+ iterationResult = IterationResult.ITERATION_COMPLETED;
- IterationResult result = checkConditionsForBalancing();
- if (result != null) {
- return result;
- }
+ // match each source node with a target
+ while (true) {
+ if (!isBalancerRunning()) {
+ iterationResult = IterationResult.ITERATION_INTERRUPTED;
+ break;
+ }
- DatanodeDetails source =
- findSourceStrategy.getNextCandidateSourceDataNode();
- if (source == null) {
- break;
- }
+ if (checkIterationLimits()) {
+ /* scheduled enough moves to hit either maxSizeToMovePerIteration or
+ maxDatanodesPercentageToInvolvePerIteration limit
+ */
+ break;
+ }
- ContainerMoveSelection moveSelection = matchSourceWithTarget(source);
- if (moveSelection != null) {
- isMoveGenerated = true;
- LOG.info("ContainerBalancer is trying to move container {} from " +
- "source datanode {} to target datanode {}",
- moveSelection.getContainerID().toString(),
- source.getUuidString(),
- moveSelection.getTargetNode().getUuidString());
-
- if (moveContainer(source, moveSelection)) {
- // consider move successful for now, and update selection criteria
- updateTargetsAndSelectionCriteria(
- selectedTargets, moveSelection, source);
- }
- } else {
- // can not find any target for this source
- findSourceStrategy.removeCandidateSourceDataNode(source);
- }
+ DatanodeDetails source =
+ findSourceStrategy.getNextCandidateSourceDataNode();
+ if (source == null) {
+ // no more source DNs are present
+ break;
}
- if (!isMoveGenerated) {
- //no move option is generated, so the cluster can not be
- //balanced any more, just stop iteration and exit
- return IterationResult.CAN_NOT_BALANCE_ANY_MORE;
+ ContainerMoveSelection moveSelection = matchSourceWithTarget(source);
+ if (moveSelection != null) {
+ isMoveGenerated = true;
+ LOG.info("ContainerBalancer is trying to move container {} from " +
+ "source datanode {} to target datanode {}",
+ moveSelection.getContainerID().toString(),
+ source.getUuidString(),
+ moveSelection.getTargetNode().getUuidString());
+
+ if (moveContainer(source, moveSelection)) {
+ // consider move successful for now, and update selection criteria
+ updateTargetsAndSelectionCriteria(
+ selectedTargets, moveSelection, source);
+ }
+ } else {
+ // can not find any target for this source
+ findSourceStrategy.removeCandidateSourceDataNode(source);
}
- return IterationResult.ITERATION_COMPLETED;
- } finally {
+ }
+ checkIterationResults(isMoveGenerated, selectedTargets);
+ return iterationResult;
+ }
+
+ /**
+ * Check the iteration results. Result can be:
+ * <p>ITERATION_INTERRUPTED if balancing was stopped</p>
+ * <p>CAN_NOT_BALANCE_ANY_MORE if no move was generated during this iteration
+ * </p>
+ * <p>ITERATION_COMPLETED</p>
+ * @param isMoveGenerated whether a move was generated during the iteration
+ * @param selectedTargets selected target datanodes
+ */
+ private void checkIterationResults(boolean isMoveGenerated,
+ Set<DatanodeDetails> selectedTargets) {
+ if (!isMoveGenerated) {
+ /*
+ If no move was generated during this iteration then we don't need to
+ check the move results
+ */
+ iterationResult = IterationResult.CAN_NOT_BALANCE_ANY_MORE;
Review comment:
I think there is a case which we might need to handle. Suppose for a
selected source datanode, no target datanode/container pair can be found. In
such case balancer will terminate as moveGenerated is false but ideally we
should exhaust all source datanodes.
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