jiajunwang commented on a change in pull request #986:
URL: https://github.com/apache/helix/pull/986#discussion_r418781001
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File path:
helix-core/src/main/java/org/apache/helix/controller/rebalancer/AbstractRebalancer.java
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@@ -305,45 +305,60 @@ public static int getStateCount(String state,
StateModelDefinition stateModelDef
Set<String> liveAndEnabled = new HashSet<>(liveInstances);
liveAndEnabled.removeAll(disabledInstancesForPartition);
- for (String state : statesPriorityList) {
- // Use the the specially ordered preferenceList for choosing instance
for top state.
- if (state.equals(statesPriorityList.get(0))) {
- List<String> preferenceListForTopState = new
ArrayList<>(preferenceList);
- Collections.sort(preferenceListForTopState,
- new TopStatePreferenceListComparator(currentStateMap,
stateModelDef));
- preferenceList = preferenceListForTopState;
- }
+ // Sort the instances based on replicas' state priority in the current
state
+ List<String> sortedPreferenceList = new ArrayList<>(preferenceList);
+ sortedPreferenceList.sort(new StatePriorityComparator(currentStateMap,
stateModelDef));
+ // Assign the state to the instances that appear in the preference list.
+ for (String state : statesPriorityList) {
int stateCount =
getStateCount(state, stateModelDef, liveAndEnabled.size(),
preferenceList.size());
for (String instance : preferenceList) {
if (stateCount <= 0) {
- break;
+ break; // continue assigning for the next state
+ }
+ if (assigned.contains(instance) || !liveAndEnabled.contains(instance))
{
+ continue; // continue checking for the next available instance
}
- if (!assigned.contains(instance) && liveAndEnabled.contains(instance))
{
- if
(HelixDefinedState.ERROR.toString().equals(currentStateMap.get(instance))) {
- bestPossibleStateMap.put(instance,
HelixDefinedState.ERROR.toString());
- } else {
- bestPossibleStateMap.put(instance, state);
- stateCount--;
+ String proposedInstance = instance;
+ // Additional check and alternate the assignment for reducing top
state handoff.
+ if (state.equals(stateModelDef.getTopState()) &&
!stateModelDef.getSecondTopStates()
Review comment:
Please consider this as a skiplist type design/implementation.
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