adixitconfluent commented on code in PR #18864:
URL: https://github.com/apache/kafka/pull/18864#discussion_r1961201931
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/assignor/SimpleAssignor.java:
##########
@@ -72,36 +77,178 @@ private GroupAssignment assignHomogenous(
if (subscribeTopicIds.isEmpty())
return new GroupAssignment(Collections.emptyMap());
- Map<Uuid, Set<Integer>> targetPartitions = computeTargetPartitions(
+ // Subscribed topic partitions for the share group.
+ List<TargetPartition> targetPartitions = computeTargetPartitions(
subscribeTopicIds, subscribedTopicDescriber);
- return new
GroupAssignment(groupSpec.memberIds().stream().collect(Collectors.toMap(
- Function.identity(), memberId -> new
MemberAssignmentImpl(targetPartitions))));
+ // The current assignment from topic partition to members.
+ Map<TargetPartition, List<String>> currentAssignment =
currentAssignment(groupSpec);
+ return newAssignmentHomogeneous(groupSpec, subscribeTopicIds,
targetPartitions, currentAssignment);
}
private GroupAssignment assignHeterogeneous(
GroupSpec groupSpec,
SubscribedTopicDescriber subscribedTopicDescriber
) {
- Map<String, MemberAssignment> members = new HashMap<>();
+ Map<String, List<TargetPartition>> memberToPartitionsSubscription =
new HashMap<>();
for (String memberId : groupSpec.memberIds()) {
MemberSubscription spec = groupSpec.memberSubscription(memberId);
if (spec.subscribedTopicIds().isEmpty())
continue;
- Map<Uuid, Set<Integer>> targetPartitions = computeTargetPartitions(
+ // Subscribed topic partitions for the share group member.
+ List<TargetPartition> targetPartitions = computeTargetPartitions(
spec.subscribedTopicIds(), subscribedTopicDescriber);
+ memberToPartitionsSubscription.put(memberId, targetPartitions);
+ }
+
+ // The current assignment from topic partition to members.
+ Map<TargetPartition, List<String>> currentAssignment =
currentAssignment(groupSpec);
+ return newAssignmentHeterogeneous(groupSpec,
memberToPartitionsSubscription, currentAssignment);
+ }
- members.put(memberId, new MemberAssignmentImpl(targetPartitions));
+ // Get the current assignment for subscribed topic partitions to share
group members.
+ private Map<TargetPartition, List<String>> currentAssignment(GroupSpec
groupSpec) {
+ Map<TargetPartition, List<String>> assignment = new HashMap<>();
+
+ for (String member : groupSpec.memberIds()) {
+ Map<Uuid, Set<Integer>> assignedTopicPartitions =
groupSpec.memberAssignment(member).partitions();
+ assignedTopicPartitions.forEach((topicId, partitions) ->
partitions.forEach(
+ partition -> assignment.computeIfAbsent(new
TargetPartition(topicId, partition), k -> new ArrayList<>()).add(member)));
}
+ return assignment;
+ }
+
+ private GroupAssignment newAssignmentHomogeneous(
+ GroupSpec groupSpec,
+ Set<Uuid> subscribeTopicIds,
+ List<TargetPartition> targetPartitions,
+ Map<TargetPartition, List<String>> currentAssignment) {
+
+ Map<TargetPartition, List<String>> newAssignment = new HashMap<>();
+ // Step 1: Hash member IDs to partitions.
+ memberHashAssignment(targetPartitions, groupSpec.memberIds(),
newAssignment);
+
+ // Step 2: Round-robin assignment for unassigned partitions which do
not have members already assigned in the current assignment.
+ Set<TargetPartition> assignedPartitions = new
HashSet<>(newAssignment.keySet());
+ List<TargetPartition> unassignedPartitions = targetPartitions.stream()
+ .filter(targetPartition ->
!assignedPartitions.contains(targetPartition))
+ .filter(targetPartition ->
!currentAssignment.containsKey(targetPartition))
+ .collect(Collectors.toList());
+
+ roundRobinAssignment(groupSpec.memberIds(), unassignedPartitions,
newAssignment);
+
+ Map<String, Set<TargetPartition>> finalAssignment = new HashMap<>();
+
+ // When combining current assignment, we need to only consider the
topics in current assignment that are also being
Review Comment:
We can do it but there will be an unnecessary change of a data structure
from `Set` to `Map` because we need a topics to member subscription for
heterogeneous (`topicToMemberSubscription`), but for homogeneous a set of
subscribed topics is enough (`subscribedTopicIds`). Hence, I'll either need to
convert the set to map to create a common function. Since it is 4-5 lines of
code only, hence I opted not to make it common.
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