jiajunwang commented on a change in pull request #525: Add waged rebalancer
monitoring mbean metrics
URL: https://github.com/apache/helix/pull/525#discussion_r338739587
##########
File path:
helix-core/src/main/java/org/apache/helix/controller/rebalancer/util/ResourceUsageCalculator.java
##########
@@ -33,4 +41,58 @@
}
return newParticipantUsage;
}
+
+ /**
+ * Count total number of all partitions in the collection of resource
assignments.
+ * @param assignments collection of resource assignments
+ * @return total number of all partitions in the collection of resource
assignments.
+ */
+ public static int
countResourceAssignmentPartitions(Collection<ResourceAssignment> assignments) {
+ return assignments.stream()
+ .mapToInt(resourceAssignment ->
resourceAssignment.getMappedPartitions().size())
+ .sum();
+ }
+
+ /**
+ * Measure baseline divergence between baseline assignment and best possible
assignment at
+ * partition level. Baseline divergence = (total number of common partitions
for each key)
+ * / (total number of different partitions for each key)
+ * @param baseline baseline assignment
+ * @param bestPossibleAssignment best possible assignment
+ * @return double value range at [0.0, 1.0]
+ */
+ public static double measureBaselineDivergence(Map<String,
ResourceAssignment> baseline,
+ Map<String, ResourceAssignment> bestPossibleAssignment) {
+ MapDifference<String, ResourceAssignment> mapDifference =
+ Maps.difference(baseline, bestPossibleAssignment);
+ Map<String, ResourceAssignment> matchedAssignment =
mapDifference.entriesInCommon();
+ Map<String, MapDifference.ValueDifference<ResourceAssignment>>
differentAssignment =
+ mapDifference.entriesDiffering();
+
+ // For each matched assignment, count all partitions and sum up.
+ int numMatchedPartitions =
countResourceAssignmentPartitions(matchedAssignment.values());
Review comment:
As we discussed, please verify the replica level divergence.
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