You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@kafka.apache.org by Christo Lolov <ch...@gmail.com> on 2026/01/19 16:27:23 UTC
[VOTE] 4.2.0 RC1
Hello Kafka users, developers and client-developers,
This is the RC1 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-rc1/RELEASE_NOTES.html
*** Please download, test and vote by Monday, January 26, 10am 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-rc1/
* Docker release artifacts to be voted upon:
apache/kafka:4.2.0-rc1
apache/kafka-native:4.2.0-rc1
* 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-rc1/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-rc1
* Documentation:
https://kafka.apache.org/42/documentation.html
* Protocol:
https://kafka.apache.org/42/protocol.html
* Successful CI builds for the 4.2 branch:
Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
at https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
There is a single failing test which I have since retried.
System tests: I have setup my E2E environment and will share test
results in the next ~24 hours.
Chia-Ping has been very generous and helpful and is also running a
parallel environment at
https://jenkins.opensource4you.tw/job/kafka-e2e/636/
* Successful Docker Image Github Actions Pipeline for 4.2 branch:
Docker Build Test Pipeline (JVM):
https://github.com/apache/kafka/actions/runs/21135593072
Docker Build Test Pipeline (Native):
https://github.com/apache/kafka/actions/runs/21136272782
Thanks,
Christo
Re: [VOTE] 4.2.0 RC1
Posted by Christo Lolov <ch...@gmail.com>.
Hello!
You can find the reports from the system tests in
https://drive.google.com/drive/folders/1mFO6S1EvwMeTrM8w-ePTiRj6ko97Sv3A?usp=sharing
The tests were ran in parallel on 4 EC2 m5.4xlarge machines with
Ubuntu 24.04 and Java 17.
The tests which failed in the first runs were reran in the second runs
i.e. client_2.txt contains a successful run of the failing tests in
client_1.txt.
Let me know if I have missed something!
Best,
Christo
On Tue, 20 Jan 2026 at 15:04, Christo Lolov <ch...@gmail.com> wrote:
>
> Heya Mickael,
>
> You are correct! I have since dropped RC0 and closed RC1 and the links
> should be pointing to artifacts from yesterday.
>
> Best,
> Christo
>
> On Tue, 20 Jan 2026 at 14:23, Rich Bowen <rb...@apache.org> wrote:
> >
> >
> >
> > On 2026/01/19 16:27:23 Christo Lolov wrote:
> > > Hello Kafka users, developers and client-developers,
> > >
> > > This is the RC1 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-rc1/RELEASE_NOTES.html
> > >
> > > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> > >
> >
> > +1 (non-binding)
> >
> > * Verified signatures and hashes on the following files as per https://apache.org/info/verification.html
> > - kafka-4.2.0-src.tgz (SHA1, SHA512, GPG signature)
> > - kafka_2.13-4.2.0-site-docs.tgz (SHA1, SHA512, GPG signature)
> > - kafka_2.13-4.2.0.tgz (SHA512, SHA1, GPG signature)
> > * Verified LICENSE and NOTICE files
> >
Re: [VOTE] 4.2.0 RC1
Posted by Christo Lolov <ch...@gmail.com>.
Heya Mickael,
You are correct! I have since dropped RC0 and closed RC1 and the links
should be pointing to artifacts from yesterday.
Best,
Christo
On Tue, 20 Jan 2026 at 14:23, Rich Bowen <rb...@apache.org> wrote:
>
>
>
> On 2026/01/19 16:27:23 Christo Lolov wrote:
> > Hello Kafka users, developers and client-developers,
> >
> > This is the RC1 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-rc1/RELEASE_NOTES.html
> >
> > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> >
>
> +1 (non-binding)
>
> * Verified signatures and hashes on the following files as per https://apache.org/info/verification.html
> - kafka-4.2.0-src.tgz (SHA1, SHA512, GPG signature)
> - kafka_2.13-4.2.0-site-docs.tgz (SHA1, SHA512, GPG signature)
> - kafka_2.13-4.2.0.tgz (SHA512, SHA1, GPG signature)
> * Verified LICENSE and NOTICE files
>
Re: [VOTE] 4.2.0 RC1
Posted by Rich Bowen <rb...@apache.org>.
On 2026/01/19 16:27:23 Christo Lolov wrote:
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
+1 (non-binding)
* Verified signatures and hashes on the following files as per https://apache.org/info/verification.html
- kafka-4.2.0-src.tgz (SHA1, SHA512, GPG signature)
- kafka_2.13-4.2.0-site-docs.tgz (SHA1, SHA512, GPG signature)
- kafka_2.13-4.2.0.tgz (SHA512, SHA1, GPG signature)
* Verified LICENSE and NOTICE files
Re: [VOTE] 4.2.0 RC1
Posted by Paolo Patierno <pa...@gmail.com>.
Hi,
we ran all tests within the Strimzi project (Apache Kafka on Kubernetes).
From regression to upgrade testing everything looks fine now.
+1 (non binding)
Thanks,
Paolo.
On Mon, 19 Jan 2026 at 17:28, Christo Lolov <ch...@gmail.com> wrote:
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at
> https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
--
Paolo Patierno
*Senior Principal Software Engineer @ IBM**CNCF Ambassador*
Twitter : @ppatierno <http://twitter.com/ppatierno>
Linkedin : paolopatierno <http://it.linkedin.com/in/paolopatierno>
GitHub : ppatierno <https://github.com/ppatierno>
[VOTE] 4.2.0 RC1
Posted by Mickael Maison <mi...@apache.org>.
Hi Christo,
It looks like you did not close the RC1 Maven artifacts in Nexus.
All the 4.2.0 artifacts are from Jan 13 so presumably it's still RC0.
For example, see
https://repository.apache.org/content/groups/staging/org/apache/kafka/kafka_2.13/4.2.0/
Thanks,
Mickael
On Mon, Jan 19, 2026 at 5:28 PM Christo Lolov <ch...@gmail.com> wrote:
>
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
> --
> You received this message because you are subscribed to the Google Groups "kafka-clients" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kafka-clients+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com.
[VOTE] 4.2.0 RC1
Posted by Mickael Maison <mi...@apache.org>.
Hi Christo,
It looks like you did not close the RC1 Maven artifacts in Nexus.
All the 4.2.0 artifacts are from Jan 13 so presumably it's still RC0.
For example, see
https://repository.apache.org/content/groups/staging/org/apache/kafka/kafka_2.13/4.2.0/
Thanks,
Mickael
On Mon, Jan 19, 2026 at 5:28 PM Christo Lolov <ch...@gmail.com> wrote:
>
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
> --
> You received this message because you are subscribed to the Google Groups "kafka-clients" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kafka-clients+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com.
Re: [VOTE] 4.2.0 RC1
Posted by Paolo Patierno <pa...@gmail.com>.
Hi,
we ran all tests within the Strimzi project (Apache Kafka on Kubernetes).
From regression to upgrade testing everything looks fine now.
+1 (non binding)
Thanks,
Paolo.
On Mon, 19 Jan 2026 at 17:28, Christo Lolov <ch...@gmail.com> wrote:
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at
> https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
--
Paolo Patierno
*Senior Principal Software Engineer @ IBM**CNCF Ambassador*
Twitter : @ppatierno <http://twitter.com/ppatierno>
Linkedin : paolopatierno <http://it.linkedin.com/in/paolopatierno>
GitHub : ppatierno <https://github.com/ppatierno>
Re: [kafka-clients] [VOTE] 4.2.0 RC1
Posted by Christo Lolov <ch...@gmail.com>.
Hey Lianet,
I will cherry-pick the commit and include it in the next release
candidate, thanks for flagging it :)
I am closing this voting thread and starting on creating the next RC!
Best,
Christo
On Mon, 26 Jan 2026 at 19:12, Lianet Magrans <li...@apache.org> wrote:
> Hey Christo, could we include this fix in the next RC? It's fixing a
> regression introduced in the java doc of the Producer (really low risk and
> important)
> https://github.com/apache/kafka/pull/21347
> If it makes sense I can cherry-pick it to 4.2
>
> Thanks!
> Lianet
>
>
> On Mon, Jan 26, 2026 at 1:52 PM Christo Lolov <ch...@gmail.com>
> wrote:
>
> > Hey Robert,
> >
> > Apologies for coming back with a delay! I observed the same things as
> > you during the qualification of the first release candidate (RC0), so
> > thank you very much for confirming!
> >
> > I filed a fix and have cherry-picked it to 4.2. I think this is
> > important enough that it necessitates another release candidate.
> >
> > Hence, I am closing this vote and will be opening a new one tomorrow.
> > If anybody is running qualification tests, I hope this gives some time
> > for you to flush any other problems out!
> >
> > Best,
> > Christo
> >
> > On Mon, 26 Jan 2026 at 13:54, Christo Lolov <ch...@gmail.com>
> > wrote:
> > >
> > > Hello Jun,
> > >
> > > The PR for the documentation/javadocs and protocol is accessible
> > > https://github.com/apache/kafka-site/pull/785, thanks for catching
> > > this!
> > > My understanding is that once the RC passes and we merge the PR it
> > > will be available on the originally mentioned URLs, but let me know if
> > > I am wrong!
> > >
> > > Best,
> > > Christo
> > >
> > > On Fri, 23 Jan 2026 at 19:53, Jun Rao via dev <de...@kafka.apache.org>
> > wrote:
> > > >
> > > > Hi, Christo,
> > > >
> > > > Thanks for preparing the RC. The links to documentation and protocol
> > are
> > > > inaccessible. Are they ready?
> > > >
> > > > Jun
> > > >
> > > > On Mon, Jan 19, 2026 at 8:28 AM Christo Lolov <
> christololov@gmail.com>
> > > > wrote:
> > > >
> > > > > Hello Kafka users, developers and client-developers,
> > > > >
> > > > > This is the RC1 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-rc1/RELEASE_NOTES.html
> > > > >
> > > > > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> > > > >
> > > > > * Docker release artifacts to be voted upon:
> > > > > apache/kafka:4.2.0-rc1
> > > > > apache/kafka-native:4.2.0-rc1
> > > > >
> > > > > * 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-rc1/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-rc1
> > > > >
> > > > > * Documentation:
> > > > > https://kafka.apache.org/42/documentation.html
> > > > >
> > > > > * Protocol:
> > > > > https://kafka.apache.org/42/protocol.html
> > > > >
> > > > > * Successful CI builds for the 4.2 branch:
> > > > > Unit/integration tests: The build for the 4.2.0-rc1 tag can be
> found
> > > > > at
> > > > >
> > https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> > > > > There is a single failing test which I have since retried.
> > > > >
> > > > > System tests: I have setup my E2E environment and will share test
> > > > > results in the next ~24 hours.
> > > > > Chia-Ping has been very generous and helpful and is also running a
> > > > > parallel environment at
> > > > > https://jenkins.opensource4you.tw/job/kafka-e2e/636/
> > > > >
> > > > > * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> > > > > Docker Build Test Pipeline (JVM):
> > > > > https://github.com/apache/kafka/actions/runs/21135593072
> > > > > Docker Build Test Pipeline (Native):
> > > > > https://github.com/apache/kafka/actions/runs/21136272782
> > > > >
> > > > > Thanks,
> > > > > Christo
> > > > >
> > > > > --
> > > > > You received this message because you are subscribed to the Google
> > Groups
> > > > > "kafka-clients" group.
> > > > > To unsubscribe from this group and stop receiving emails from it,
> > send an
> > > > > email to kafka-clients+unsubscribe@googlegroups.com.
> > > > > To view this discussion visit
> > > > >
> >
> https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com
> > > > > .
> > > > >
> >
>
Re: [kafka-clients] [VOTE] 4.2.0 RC1
Posted by Lianet Magrans <li...@apache.org>.
Hey Christo, could we include this fix in the next RC? It's fixing a
regression introduced in the java doc of the Producer (really low risk and
important)
https://github.com/apache/kafka/pull/21347
If it makes sense I can cherry-pick it to 4.2
Thanks!
Lianet
On Mon, Jan 26, 2026 at 1:52 PM Christo Lolov <ch...@gmail.com>
wrote:
> Hey Robert,
>
> Apologies for coming back with a delay! I observed the same things as
> you during the qualification of the first release candidate (RC0), so
> thank you very much for confirming!
>
> I filed a fix and have cherry-picked it to 4.2. I think this is
> important enough that it necessitates another release candidate.
>
> Hence, I am closing this vote and will be opening a new one tomorrow.
> If anybody is running qualification tests, I hope this gives some time
> for you to flush any other problems out!
>
> Best,
> Christo
>
> On Mon, 26 Jan 2026 at 13:54, Christo Lolov <ch...@gmail.com>
> wrote:
> >
> > Hello Jun,
> >
> > The PR for the documentation/javadocs and protocol is accessible
> > https://github.com/apache/kafka-site/pull/785, thanks for catching
> > this!
> > My understanding is that once the RC passes and we merge the PR it
> > will be available on the originally mentioned URLs, but let me know if
> > I am wrong!
> >
> > Best,
> > Christo
> >
> > On Fri, 23 Jan 2026 at 19:53, Jun Rao via dev <de...@kafka.apache.org>
> wrote:
> > >
> > > Hi, Christo,
> > >
> > > Thanks for preparing the RC. The links to documentation and protocol
> are
> > > inaccessible. Are they ready?
> > >
> > > Jun
> > >
> > > On Mon, Jan 19, 2026 at 8:28 AM Christo Lolov <ch...@gmail.com>
> > > wrote:
> > >
> > > > Hello Kafka users, developers and client-developers,
> > > >
> > > > This is the RC1 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-rc1/RELEASE_NOTES.html
> > > >
> > > > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> > > >
> > > > * Docker release artifacts to be voted upon:
> > > > apache/kafka:4.2.0-rc1
> > > > apache/kafka-native:4.2.0-rc1
> > > >
> > > > * 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-rc1/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-rc1
> > > >
> > > > * Documentation:
> > > > https://kafka.apache.org/42/documentation.html
> > > >
> > > > * Protocol:
> > > > https://kafka.apache.org/42/protocol.html
> > > >
> > > > * Successful CI builds for the 4.2 branch:
> > > > Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> > > > at
> > > >
> https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> > > > There is a single failing test which I have since retried.
> > > >
> > > > System tests: I have setup my E2E environment and will share test
> > > > results in the next ~24 hours.
> > > > Chia-Ping has been very generous and helpful and is also running a
> > > > parallel environment at
> > > > https://jenkins.opensource4you.tw/job/kafka-e2e/636/
> > > >
> > > > * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> > > > Docker Build Test Pipeline (JVM):
> > > > https://github.com/apache/kafka/actions/runs/21135593072
> > > > Docker Build Test Pipeline (Native):
> > > > https://github.com/apache/kafka/actions/runs/21136272782
> > > >
> > > > Thanks,
> > > > Christo
> > > >
> > > > --
> > > > You received this message because you are subscribed to the Google
> Groups
> > > > "kafka-clients" group.
> > > > To unsubscribe from this group and stop receiving emails from it,
> send an
> > > > email to kafka-clients+unsubscribe@googlegroups.com.
> > > > To view this discussion visit
> > > >
> https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com
> > > > .
> > > >
>
Re: [kafka-clients] [VOTE] 4.2.0 RC1
Posted by Christo Lolov <ch...@gmail.com>.
Hey Robert,
Apologies for coming back with a delay! I observed the same things as
you during the qualification of the first release candidate (RC0), so
thank you very much for confirming!
I filed a fix and have cherry-picked it to 4.2. I think this is
important enough that it necessitates another release candidate.
Hence, I am closing this vote and will be opening a new one tomorrow.
If anybody is running qualification tests, I hope this gives some time
for you to flush any other problems out!
Best,
Christo
On Mon, 26 Jan 2026 at 13:54, Christo Lolov <ch...@gmail.com> wrote:
>
> Hello Jun,
>
> The PR for the documentation/javadocs and protocol is accessible
> https://github.com/apache/kafka-site/pull/785, thanks for catching
> this!
> My understanding is that once the RC passes and we merge the PR it
> will be available on the originally mentioned URLs, but let me know if
> I am wrong!
>
> Best,
> Christo
>
> On Fri, 23 Jan 2026 at 19:53, Jun Rao via dev <de...@kafka.apache.org> wrote:
> >
> > Hi, Christo,
> >
> > Thanks for preparing the RC. The links to documentation and protocol are
> > inaccessible. Are they ready?
> >
> > Jun
> >
> > On Mon, Jan 19, 2026 at 8:28 AM Christo Lolov <ch...@gmail.com>
> > wrote:
> >
> > > Hello Kafka users, developers and client-developers,
> > >
> > > This is the RC1 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-rc1/RELEASE_NOTES.html
> > >
> > > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> > >
> > > * Docker release artifacts to be voted upon:
> > > apache/kafka:4.2.0-rc1
> > > apache/kafka-native:4.2.0-rc1
> > >
> > > * 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-rc1/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-rc1
> > >
> > > * Documentation:
> > > https://kafka.apache.org/42/documentation.html
> > >
> > > * Protocol:
> > > https://kafka.apache.org/42/protocol.html
> > >
> > > * Successful CI builds for the 4.2 branch:
> > > Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> > > at
> > > https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> > > There is a single failing test which I have since retried.
> > >
> > > System tests: I have setup my E2E environment and will share test
> > > results in the next ~24 hours.
> > > Chia-Ping has been very generous and helpful and is also running a
> > > parallel environment at
> > > https://jenkins.opensource4you.tw/job/kafka-e2e/636/
> > >
> > > * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> > > Docker Build Test Pipeline (JVM):
> > > https://github.com/apache/kafka/actions/runs/21135593072
> > > Docker Build Test Pipeline (Native):
> > > https://github.com/apache/kafka/actions/runs/21136272782
> > >
> > > Thanks,
> > > Christo
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups
> > > "kafka-clients" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an
> > > email to kafka-clients+unsubscribe@googlegroups.com.
> > > To view this discussion visit
> > > https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com
> > > .
> > >
Re: [kafka-clients] [VOTE] 4.2.0 RC1
Posted by Christo Lolov <ch...@gmail.com>.
Hello Jun,
The PR for the documentation/javadocs and protocol is accessible
https://github.com/apache/kafka-site/pull/785, thanks for catching
this!
My understanding is that once the RC passes and we merge the PR it
will be available on the originally mentioned URLs, but let me know if
I am wrong!
Best,
Christo
On Fri, 23 Jan 2026 at 19:53, Jun Rao via dev <de...@kafka.apache.org> wrote:
>
> Hi, Christo,
>
> Thanks for preparing the RC. The links to documentation and protocol are
> inaccessible. Are they ready?
>
> Jun
>
> On Mon, Jan 19, 2026 at 8:28 AM Christo Lolov <ch...@gmail.com>
> wrote:
>
> > Hello Kafka users, developers and client-developers,
> >
> > This is the RC1 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-rc1/RELEASE_NOTES.html
> >
> > *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
> >
> > * Docker release artifacts to be voted upon:
> > apache/kafka:4.2.0-rc1
> > apache/kafka-native:4.2.0-rc1
> >
> > * 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-rc1/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-rc1
> >
> > * Documentation:
> > https://kafka.apache.org/42/documentation.html
> >
> > * Protocol:
> > https://kafka.apache.org/42/protocol.html
> >
> > * Successful CI builds for the 4.2 branch:
> > Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> > at
> > https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> > There is a single failing test which I have since retried.
> >
> > System tests: I have setup my E2E environment and will share test
> > results in the next ~24 hours.
> > Chia-Ping has been very generous and helpful and is also running a
> > parallel environment at
> > https://jenkins.opensource4you.tw/job/kafka-e2e/636/
> >
> > * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> > Docker Build Test Pipeline (JVM):
> > https://github.com/apache/kafka/actions/runs/21135593072
> > Docker Build Test Pipeline (Native):
> > https://github.com/apache/kafka/actions/runs/21136272782
> >
> > Thanks,
> > Christo
> >
> > --
> > You received this message because you are subscribed to the Google Groups
> > "kafka-clients" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
> > email to kafka-clients+unsubscribe@googlegroups.com.
> > To view this discussion visit
> > https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com
> > .
> >
Re: [kafka-clients] [VOTE] 4.2.0 RC1
Posted by Jun Rao via dev <de...@kafka.apache.org>.
Hi, Christo,
Thanks for preparing the RC. The links to documentation and protocol are
inaccessible. Are they ready?
Jun
On Mon, Jan 19, 2026 at 8:28 AM Christo Lolov <ch...@gmail.com>
wrote:
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at
> https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
> --
> You received this message because you are subscribed to the Google Groups
> "kafka-clients" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to kafka-clients+unsubscribe@googlegroups.com.
> To view this discussion visit
> https://groups.google.com/d/msgid/kafka-clients/CANF%2Ba5c5USZr9TG1YrXcg9zuy2tnZdgC4MyW6QYtJ30eR_5VvQ%40mail.gmail.com
> .
>
Re: [VOTE] 4.2.0 RC1
Posted by Robert Young <ro...@redhat.com>.
Hi!
The docker quickstart command is failing for me:
podman run -p 9092:9092 apache/kafka:4.2.0-rc1
===> User
uid=1000(appuser) gid=1000(appuser) groups=1000(appuser)
===> Setting default values of environment variables if not already set.
CLUSTER_ID not set. Setting it to default value: "5L6g3nShT-eMCtK--X86sw"
===> Configuring ...
===> Launching ...
===> Using provided cluster id 5L6g3nShT-eMCtK--X86sw ...
Exception in thread "main" org.apache.kafka.common.config.ConfigException:
Missing required configuration "process.roles" which has no default value.
at org.apache.kafka.common.config.ConfigDef.parseValue(ConfigDef.java:537)
at org.apache.kafka.common.config.ConfigDef.parse(ConfigDef.java:527) at
org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:118)
at
org.apache.kafka.server.config.AbstractKafkaConfig.<init>(AbstractKafkaConfig.java:78)
at kafka.server.KafkaConfig.<init>(KafkaConfig.scala:155) at
kafka.server.KafkaConfig.<init>(KafkaConfig.scala:157) at
kafka.tools.StorageTool$.$anonfun$execute$1(StorageTool.scala:79) at
scala.Option.flatMap(Option.scala:283) at
kafka.tools.StorageTool$.execute(StorageTool.scala:79) at
kafka.tools.StorageTool$.main(StorageTool.scala:46) at
kafka.docker.KafkaDockerWrapper$.main(KafkaDockerWrapper.scala:57) at
kafka.docker.KafkaDockerWrapper.main(KafkaDockerWrapper.scala)
I think the difference is there is a KAFKA_ environment variable set in the
image
podman run --rm -it --entrypoint env apache/kafka:4.2.0-rc1 | grep KAFKA
KAFKA_URL=
https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc1/kafka_2.13-4.2.0.tgz
which isn't present in 4.1.1. Leading to
/opt/kafka/config/server.properties being generated containing:
$ container=$(podman run --detach -p 9092:9092 apache/kafka:4.2.0-rc1)
$ podman cp ${container}:/opt/kafka/config/server.properties .
$ cat server.properties
url=
https://dist.apache.org/repos/dist/dev/kafka/4.2.0-rc1/kafka_2.13-4.2.0.tgz
Thanks
Rob
On Tue, Jan 20, 2026 at 5:36 AM Christo Lolov <ch...@gmail.com>
wrote:
> Hello Kafka users, developers and client-developers,
>
> This is the RC1 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-rc1/RELEASE_NOTES.html
>
> *** Please download, test and vote by Monday, January 26, 10am 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-rc1/
>
> * Docker release artifacts to be voted upon:
> apache/kafka:4.2.0-rc1
> apache/kafka-native:4.2.0-rc1
>
> * 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-rc1/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-rc1
>
> * Documentation:
> https://kafka.apache.org/42/documentation.html
>
> * Protocol:
> https://kafka.apache.org/42/protocol.html
>
> * Successful CI builds for the 4.2 branch:
> Unit/integration tests: The build for the 4.2.0-rc1 tag can be found
> at
> https://github.com/apache/kafka/actions/runs/21135565337/job/60779418474
> There is a single failing test which I have since retried.
>
> System tests: I have setup my E2E environment and will share test
> results in the next ~24 hours.
> Chia-Ping has been very generous and helpful and is also running a
> parallel environment at
> https://jenkins.opensource4you.tw/job/kafka-e2e/636/
>
> * Successful Docker Image Github Actions Pipeline for 4.2 branch:
> Docker Build Test Pipeline (JVM):
> https://github.com/apache/kafka/actions/runs/21135593072
> Docker Build Test Pipeline (Native):
> https://github.com/apache/kafka/actions/runs/21136272782
>
> Thanks,
> Christo
>
>