jiajunwang commented on a change in pull request #1098:
URL: https://github.com/apache/helix/pull/1098#discussion_r441900941
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File path:
helix-core/src/main/java/org/apache/helix/controller/rebalancer/AbstractRebalancer.java
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@@ -385,10 +389,19 @@ public static int getStateCount(String state,
StateModelDefinition stateModelDef
// If the desired state is the top state, but the instance cannot be
transited to the
// top state in one hop, try to keep the top state on current host
or a host with a closer
// state.
- for (String currentStatePrioritizedInstance : sortedPreferenceList) {
- if (!assigned.contains(currentStatePrioritizedInstance) &&
liveAndEnabled
- .contains(currentStatePrioritizedInstance)) {
+ while (currentStatePrioritizedInstanceIter.hasNext()) {
+ // Note that it is safe to check the prioritized instance items
only once here.
+ // Since the only possible condition when we don't use an instance
in this list is that
+ // it has been assigned with some state. And this is not
revertable in this method. So
+ // checking it one more time later will only waste time.
+ String currentStatePrioritizedInstance =
currentStatePrioritizedInstanceIter.next();
+ if (!assigned.contains(currentStatePrioritizedInstance)) {
proposedInstance = currentStatePrioritizedInstance;
+ // If we find a different instance for the partition placement,
then we need to check
+ // the same instance again or it will not be assigned with any
partitions.
+ if (!proposedInstance.equals(instance)) {
+ i--;
Review comment:
I tried it, with some enhancement, the performance is actually slightly
better.
The only downside is that we introduced many more changes to make it
clearer. Please review the new change.
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