Hello Mickael, In my opinion KAFKA-20115 is a blocker and necessitates another RC once merged. My hope is that one will be the last RC for 4.2.0. Let me know if you disagree with the classification.
Hello Matthias, Before I prepare a new RC, I will cherry-pick the changes. Best, Christo > On 7 Feb 2026, at 00:03, Matthias J. Sax <[email protected]> wrote: > > Hello, > > If we do a new RC, can we merge and cherry-pick two minor docs PRs? > > - https://github.com/apache/kafka/pull/21366 > - https://github.com/apache/kafka/pull/21397 > > Both already approved -- did just hold off to merge to `trunk`, to not later > forget to do the cherry-pick. > > > I also just approved a bug-fix for > https://issues.apache.org/jira/browse/KAFKA-19960 > (https://github.com/apache/kafka/pull/21365) which is a critical bug. Also ok > to only get into 4.2.1, but of course better to get into 4.2.0 directly if > there is no objection? > > > -Matthias > > >> On 2/6/26 6:59 AM, Mickael Maison wrote: >> Hi Christo, >> Can you clarify how you've triaged >> https://issues.apache.org/jira/browse/KAFKA-20115? >> Is it a regression that requires a new RC or not? >> Thanks, >> Mickael >>> On Tue, Feb 3, 2026 at 7:00 PM Sean Quah via dev <[email protected]> >>> wrote: >>> >>> Hi all, >>> Unfortunately we discovered a regression in 4.2 today: >>> https://issues.apache.org/jira/browse/KAFKA-20115 >>> The impact is that when we have a group coordinator leadership change in >>> the middle of consumer group rebalancing, we can leave parked JoinGroup and >>> SyncGroup requests hanging until clients time out the request. I think the >>> timeout interval is the rebalance timeout/max.poll.interval.ms which is 5 >>> minutes long by default, so it can be fairly disruptive to consumer >>> applications. >>> >>> A fix is in progress at https://github.com/apache/kafka/pull/21396. >>> >>> Thanks, >>> Sean >>> >>>> On Mon, Feb 2, 2026 at 4:42 PM Christo Lolov <[email protected]> >>>> wrote: >>> >>>> Hello Kafka users, developers and client-developers, >>>> >>>> This is the RC3 candidate for release of Apache Kafka 4.2.0. >>>> >>>> This release has many exciting changes: >>>> * Kafka Queues (Share Groups) is now production-ready with new >>>> features like the RENEW acknowledgement type for extended processing >>>> times, adaptive batching for coordinators, and comprehensive lag >>>> metrics. >>>> * Kafka Streams brings the server-side rebalance protocol to GA with a >>>> limited feature set, adds dead letter queue support in exception >>>> handlers, introduces anchored wall-clock punctuation for deterministic >>>> scheduling, and gives users full control over whether to send a leave >>>> group request on closing. >>>> * This release also delivers significant improvements to consistency >>>> and observability: CLI tools now feature standardized arguments like >>>> --bootstrap-server across all tools, metric naming has been corrected >>>> to follow the kafka.COMPONENT convention, and new idle ratio metrics >>>> provide better visibility into controller and MetadataLoader >>>> performance. >>>> * Security is enhanced with a new allowlist connector client >>>> configuration override policy, while thread-safety improvements to >>>> RecordHeader eliminate concurrency risks. >>>> * Additional highlights include external schema support in >>>> JsonConverter for reduced message sizes, dynamic configuration for >>>> remote log manager thread pools, and rack ID exposure in the Admin API >>>> for consumer and share group members. >>>> >>>> Release notes for the 4.2.0 release: >>>> https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc3/RELEASE_NOTES.html >>>> >>>> *** Please download, test and vote by Thursday, February 5, 5pm UTC >>>> >>>> Kafka's KEYS file containing PGP keys we use to sign the release: >>>> https://kafka.apache.org/KEYS >>>> >>>> * Release artifacts to be voted upon (source and binary): >>>> https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc3/ >>>> >>>> * Docker release artifacts to be voted upon: >>>> apache/kafka:4.2.0-rc3 >>>> apache/kafka-native:4.2.0-rc3 >>>> >>>> * Maven artifacts to be voted upon: >>>> https://repository.apache.org/content/groups/staging/org/apache/kafka/ >>>> >>>> * Javadoc: >>>> https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc3/javadoc/index.html >>>> >>>> * Tag to be voted upon (off 4.2 branch) is the 4.2.0 tag: >>>> https://github.com/apache/kafka/releases/tag/4.2.0-rc3 >>>> >>>> * Documentation: >>>> * Protocol: >>>> https://github.com/apache/kafka-site/pull/785 >>>> >>>> * Successful CI builds for the 4.2 branch: >>>> Unit/integration tests: >>>> https://github.com/apache/kafka/actions/runs/21591368372 >>>> System tests: I have started the tests in my environment and will share >>>> test >>>> results in the next ~24 hours. >>>> >>>> * Successful Docker Image Github Actions Pipeline for 4.2 branch: >>>> Docker Build Test Pipeline (JVM): >>>> https://github.com/apache/kafka/actions/runs/21591979775 >>>> Docker Build Test Pipeline (Native): >>>> https://github.com/apache/kafka/actions/runs/21592431252 >>>> >>>> Thanks, >>>> Christo >>>> >
