jolshan commented on code in PR #16898:
URL: https://github.com/apache/kafka/pull/16898#discussion_r1725409559
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group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -848,26 +844,32 @@ ConsumerGroup consumerGroup(
ConsumerGroup getOrMaybeCreatePersistedConsumerGroup(
String groupId,
boolean createIfNotExists
- ) throws GroupIdNotFoundException {
+ ) throws IllegalStateException {
Group group = groups.get(groupId);
if (group == null && !createIfNotExists) {
- throw new IllegalStateException(String.format("Consumer group %s
not found.", groupId));
+ throw new IllegalStateException(String.format("Consumer group %s
not found", groupId));
}
if (group == null) {
ConsumerGroup consumerGroup = new ConsumerGroup(snapshotRegistry,
groupId, metrics);
groups.put(groupId, consumerGroup);
metrics.onConsumerGroupStateTransition(null,
consumerGroup.state());
return consumerGroup;
+ } else if (group.type() == CONSUMER) {
+ return (ConsumerGroup) group;
+ } else if (group.type() == CLASSIC && ((ClassicGroup)
group).isSimpleGroup()) {
+ // If the group is a simple classic group, it was automatically
created to hold committed
+ // offsets if no group existed. Simple classic groups are not
backed by any records
+ // in the __consumer_offsets topic hence we can safely replace it
here. Without this,
+ // replaying consumer group records after offset commit records
would not work.
Review Comment:
Just for my understanding -- these issues are all stemming from that when we
designed the replay logic, we assumed the records would be as when they were
first written, but since we compact, we may remove records (turn to tombstones
case 1) or we may remove records that create groups and this was handled badly
in cases 2 and 3
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