jiajunwang commented on a change in pull request #639: Refine the WAGED
rebalancer to minimize the partial rebalance workload.
URL: https://github.com/apache/helix/pull/639#discussion_r352899469
##########
File path:
helix-core/src/main/java/org/apache/helix/controller/rebalancer/waged/model/ClusterModelProvider.java
##########
@@ -93,42 +187,126 @@ public static ClusterModel
generateClusterModel(ResourceControllerDataProvider d
return new ClusterModel(context, toBeAssignedReplicas, assignableNodes);
}
+ // Filter the replicas map so only the replicas that have been allocated in
the existing
+ // assignmentMap remain in the map.
+ private static void removeUnknownReplicas(Map<String,
Set<AssignableReplica>> replicaMap,
+ Map<String, ResourceAssignment> assignmentMap) {
+ replicaMap.entrySet().parallelStream().forEach(replicaSetEntry -> {
+ // <partition, <state, instances set>>
+ Map<String, Map<String, Set<String>>> stateInstanceMap =
+ getStateInstanceMap(assignmentMap.get(replicaSetEntry.getKey()));
+ // Iterate the replicas of the resource to find the ones that require
reallocating.
+ Iterator<AssignableReplica> replicaIter =
replicaSetEntry.getValue().iterator();
+ while (replicaIter.hasNext()) {
+ AssignableReplica replica = replicaIter.next();
+ Set<String> validInstances =
+ stateInstanceMap.getOrDefault(replica.getPartitionName(),
Collections.emptyMap())
+ .getOrDefault(replica.getReplicaState(),
Collections.emptySet());
+ if (validInstances.isEmpty()) {
+ // Removing by comparing with the baseline assignment.
+ replicaIter.remove();
+ } else {
+ // Cleanup the state map record, so the selected instance won't be
picked up again for
+ // the other replica checkup.
+ validInstances.remove(validInstances.iterator().next());
+ }
+ }
+ });
+ }
+
/**
- * Generate a cluster model based on the current state output and data cache.
- * @param dataProvider The controller's data cache.
- * @param resourceMap The full list of the resources to be
rebalanced. Note that any
- * resources that are not in this list will be
removed from the
- * final assignment.
- * @param currentStateAssignment The resource assignment built from current
state output.
- * @return A cluster model based on the current state and data cache.
+ * Find the minimum set of replicas that need to be reassigned by comparing
with the Baseline
+ * assignment.
+ * A replica needs to be reassigned if one of the following conditions is
true:
+ * 1. The assignments in the Baseline and the Best possible assignment are
different. And the
+ * assignment in the Baseline is valid. So it is worthwhile to move it.
+ * 2. The assignments is not in the Baseline or the Best possible assignment.
+ * Otherwise, the rebalancer just keeps the current Best possible assignment
allocation.
+ *
+ * @param replicaMap A map contains all the replicas grouped by
resource name.
+ * @param activeInstances All the instances that are live and enabled
according to the delay rebalance configuration.
+ * @param baselineAssignment The baseline assignment.
+ * @param bestPossibleAssignment The current best possible assignment.
Review comment:
Good catch. But I prefer to change it the reverse way for
findToBeAssignedReplicasByClusterChanges. That method is not only used to
calculated based on the best possible assignment. So keep the description and
param names in this method generic.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
With regards,
Apache Git Services
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
