Thanks David, I saw that the fix to KAFKA-20115 landed in 4.2 earlier today!
Thanks Matthias, I have now merged 21423 into 4.2 alongside https://github.com/apache/kafka/pull/21366 and https://github.com/apache/kafka/pull/21397. I am now closing the vote for RC3 and will be raising a new RC tomorrow morning (this gives a chance for some last-minute changes if any are uncovered :)) with the aim to get a vote by Friday this week! Best, Christo On Mon, 9 Feb 2026 at 19:38, Matthias J. Sax <[email protected]> wrote: > Thanks Christo, > > For the bug-fix, it doesn't cherry-pick cleanly, so we prepared a PR for > it: https://github.com/apache/kafka/pull/21423 > > -Matthias > > On 2/9/26 12:01 AM, David Jacot via dev wrote: > > Hey all, > > > > While I agree that KAFKA-20115 is not a regression in 4.2, I think that > > releasing 4.2 without the fix would be really bad as it impacts all > groups > > using the classic protocol. They experience long rebalances when the > > underlying __consumer_offsets hosting them is reassigned in the cluster, > > which is common with tools such as Cruise Control. It is pretty > disruptive. > > > > Best, > > David > > > > On Sun, Feb 8, 2026 at 12:32 PM Christo Lolov <[email protected]> > > wrote: > > > >> 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 > >>>>>> > >>> > >> > > > >
