adixitconfluent commented on code in PR #19142:
URL: https://github.com/apache/kafka/pull/19142#discussion_r1984521190
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/assignor/SimpleAssignor.java:
##########
@@ -135,56 +148,68 @@ private GroupAssignment newAssignmentHomogeneous(
List<TopicIdPartition> targetPartitions,
Map<TopicIdPartition, List<String>> currentAssignment
) {
- Map<TopicIdPartition, List<String>> newAssignment = new HashMap<>();
-
- // Step 1: Hash member IDs to topic partitions.
- memberHashAssignment(targetPartitions, groupSpec.memberIds(),
newAssignment);
+ int numGroupMembers = groupSpec.memberIds().size();
+ int numTargetPartitions = targetPartitions.size();
+ int desiredAssignmentCount = (numTargetPartitions + numGroupMembers -
1) / numGroupMembers;
- // Step 2: Round-robin assignment for unassigned partitions which do
not have members already assigned in the current assignment.
- List<TopicIdPartition> unassignedPartitions = targetPartitions.stream()
- .filter(targetPartition ->
!newAssignment.containsKey(targetPartition))
- .filter(targetPartition ->
!currentAssignment.containsKey(targetPartition))
- .toList();
+ Map<TopicIdPartition, List<String>> newAssignment = new
HashMap<>((int) (((numTargetPartitions + 1) / 0.75f) + 1));
Review Comment:
What's the rationale behind using 0.75f and not some other arbitrary number?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/assignor/SimpleAssignor.java:
##########
@@ -135,56 +148,68 @@ private GroupAssignment newAssignmentHomogeneous(
List<TopicIdPartition> targetPartitions,
Map<TopicIdPartition, List<String>> currentAssignment
) {
- Map<TopicIdPartition, List<String>> newAssignment = new HashMap<>();
-
- // Step 1: Hash member IDs to topic partitions.
- memberHashAssignment(targetPartitions, groupSpec.memberIds(),
newAssignment);
+ int numGroupMembers = groupSpec.memberIds().size();
+ int numTargetPartitions = targetPartitions.size();
+ int desiredAssignmentCount = (numTargetPartitions + numGroupMembers -
1) / numGroupMembers;
Review Comment:
I wanted to understand how we came up with the number?
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