Add 4.2 blog post #786

clolov · 2026-01-14T17:38:13Z

mjsax · 2026-01-15T01:28:41Z

content/en/blog/releases/ak-4.2.0.md

+
+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 gains dead letter queue support in exception handlers, anchored wall-clock punctuation for deterministic scheduling, and the new server-side rebalance protocol reaches GA with a limited feature set.


Suggested change

Kafka Streams gains dead letter queue support in exception handlers, anchored wall-clock punctuation for deterministic scheduling, and the new server-side rebalance protocol reaches GA with a limited feature set.

Kafka Streams gains the new server-side rebalance protocol reaches GA with a limited feature set, dead letter queue support in exception handlers, and anchored wall-clock punctuation for deterministic scheduling.

I would lead with 1071 as it's the most impactful.

Should we add https://cwiki.apache.org/confluence/display/KAFKA/KIP-1153%3A+Refactor+Kafka+Streams+CloseOptions+to+Fluent+API+Style -- The key is, that with this feature users now gain full control to send or not send a leave group request on close(...). -- The KIP title is unfortunately not highlighting this but it sounds more like API cleanup, while it's actually much more.

Implemented your suggestions in the latest version 😊

content/en/blog/releases/ak-4.2.0.md

mjsax · 2026-01-15T01:37:11Z

content/en/blog/releases/ak-4.2.0.md

+  Introduces anchored wall-clock punctuation for Kafka Streams by adding an optional `startTime` parameter to `schedule()`, enabling callbacks at fixed, deterministic times (e.g., exactly at the start of every hour).
+
+* [KIP-1153: Refactor Kafka Streams CloseOptions to Fluent API Style](https://cwiki.apache.org/confluence/x/QAq9F)    
+  Introduces a new fluent-style `CloseOptions` class for Kafka Streams with a `GroupMembershipOperation` enum, improving readability and consistency with other configuration classes.


While this KIP does some API cleanup, the key is actually to give full control to users to send or not send a "leave group request" on close(...).

Reworded in the latest version to highlight your point!

content/en/blog/releases/ak-4.2.0.md

mjsax · 2026-01-15T01:42:28Z

content/en/blog/releases/ak-4.2.0.md

+Ready to get started with Apache Kafka 4.2.0? Check out all the details in the [upgrade notes](https://kafka.apache.org/documentation.html#upgrade_4_2_0) and the [release notes](https://downloads.apache.org/kafka/4.2.0/RELEASE_NOTES.html), and [download](https://kafka.apache.org/downloads) Apache Kafka 4.2.0.
+
+This was a community effort, so thank you to everyone who contributed to this release, including all our users and our 169 contributors:  
+@brandboat, @m1a2st, bbejeck@apache.org, Abhi Tiwari, Abhijeet Kumar, Abhinav Dixit, Abhiram98, Alex, Alieh Saeedi, ally heev, Alyssa Huang, Andrew J Schofield, Anton Vasanth, Apoorv Mittal, Arpit Goyal, Artem Livshits, Bill Bejeck, Bolin Lin, Bruno Cadonna, Calvin Liu, Chang-Chi Hsu, Chang-Yu Huang, Chia-Ping Tsai, Chih-Yuan Chien, Chirag Wadhwa, Chris Egerton, Christo Lolov, Chuckame, Clemens Hutter, Colin Patrick McCabe, d00791190, Dave Troiano, David Arthur, David Jacot, Deep Golani, Dejan Stojadinović, devtrace404, Dmitry Werner, Dongnuo Lyu, Donny Nadolny, Eduwer Camacaro, Elizabeth Bennett, EME, Eric Chang, Erik Anderson, Evan Zhou, Evanston Zhou, Evgeniy Kuvardin, farzan ghalami, Fatih, Federico Valeri, Gantigmaa Selenge, Gasparina Damien, Gaurav Narula, Genseric Ghiro, George Wu, Greg Harris, Harish Vishwanath, Herman Kolstad Jakobsen, Hong-Yi Chen, Ismael Juma, Izzy Harker, Jared Harley, Jhen-Yung Hsu, Jian, Jim Galasyn, jimmy, Jimmy Wang, Jing-Jia Hung, Jinhe Zhang, Joel Hamill, Jonah Hooper, Josep Prat, José Armando García Sancio, Juha Mynttinen, Jun Rao, Justine Olshan, k-apol, Kamal Chandraprakash, Kaushik Raina, keemsisi, Ken Huang, Kevin Wu, Kirk True, knoxy5467, KTKTK-HZ, Kuan-Po Tseng, Lan Ding, Levani Kokhreidze, Liam Clarke-Hutchinson, Lianet Magrans, Linsiyuan9, Logan Zhu, lorcan, Lord of Abyss, Lucas Brutschy, lucliu1108, Luke Chen, Mahsa Seifikar, majialong, Manikumar Reddy, Maros Orsak, Masahiro Mori, Mason Chen, Matt Welch, Matthias J. Sax, Matthias Sax, Michael Knox, Michael Morris, Mickael Maison, Ming-Yen Chung, NeatGuyCoding, Nick Guo, NICOLAS GUYOMAR, Nikita Shupletsov, Now, Okada Haruki, Omnia Ibrahim, Otmar Ertl, OuO, Paolo Patierno, Patrik Nagy, Pawel Szymczyk, PoAn Yang, Ken Huang, Ken Huang, Priyanka K U, Rajani K, Rajini Sivaram, Ram, Ritika Reddy, Robert Young, Ryan Dielhenn, S.Y. Wang, samarth-ksolves, Sanskar Jhajharia, Satish Duggana, Sean Quah, Sebastien Viale, Shang-Hao Yang, Shashank, Shivsundar R, ShivsundarR, Siyang He, Sophie Blee-Goldman, Stig Døssing, stroller, stroller.fu, Sushant Mahajan, TaiJuWu, TengYao Chi, Tsung-Han Ho (Miles Ho), Ubuntu, Uladzislau Blok, Vincent PÉRICART, Xiao Yang, xijiu, Xuan-Zhang Gong, yangxuze, Yeikel Santana, Yu-Syuan Jheng, YuChia Ma, Yunchi Pang, Yung


Suggested change

@brandboat, @m1a2st, bbejeck@apache.org, Abhi Tiwari, Abhijeet Kumar, Abhinav Dixit, Abhiram98, Alex, Alieh Saeedi, ally heev, Alyssa Huang, Andrew J Schofield, Anton Vasanth, Apoorv Mittal, Arpit Goyal, Artem Livshits, Bill Bejeck, Bolin Lin, Bruno Cadonna, Calvin Liu, Chang-Chi Hsu, Chang-Yu Huang, Chia-Ping Tsai, Chih-Yuan Chien, Chirag Wadhwa, Chris Egerton, Christo Lolov, Chuckame, Clemens Hutter, Colin Patrick McCabe, d00791190, Dave Troiano, David Arthur, David Jacot, Deep Golani, Dejan Stojadinović, devtrace404, Dmitry Werner, Dongnuo Lyu, Donny Nadolny, Eduwer Camacaro, Elizabeth Bennett, EME, Eric Chang, Erik Anderson, Evan Zhou, Evanston Zhou, Evgeniy Kuvardin, farzan ghalami, Fatih, Federico Valeri, Gantigmaa Selenge, Gasparina Damien, Gaurav Narula, Genseric Ghiro, George Wu, Greg Harris, Harish Vishwanath, Herman Kolstad Jakobsen, Hong-Yi Chen, Ismael Juma, Izzy Harker, Jared Harley, Jhen-Yung Hsu, Jian, Jim Galasyn, jimmy, Jimmy Wang, Jing-Jia Hung, Jinhe Zhang, Joel Hamill, Jonah Hooper, Josep Prat, José Armando García Sancio, Juha Mynttinen, Jun Rao, Justine Olshan, k-apol, Kamal Chandraprakash, Kaushik Raina, keemsisi, Ken Huang, Kevin Wu, Kirk True, knoxy5467, KTKTK-HZ, Kuan-Po Tseng, Lan Ding, Levani Kokhreidze, Liam Clarke-Hutchinson, Lianet Magrans, Linsiyuan9, Logan Zhu, lorcan, Lord of Abyss, Lucas Brutschy, lucliu1108, Luke Chen, Mahsa Seifikar, majialong, Manikumar Reddy, Maros Orsak, Masahiro Mori, Mason Chen, Matt Welch, Matthias J. Sax, Matthias Sax, Michael Knox, Michael Morris, Mickael Maison, Ming-Yen Chung, NeatGuyCoding, Nick Guo, NICOLAS GUYOMAR, Nikita Shupletsov, Now, Okada Haruki, Omnia Ibrahim, Otmar Ertl, OuO, Paolo Patierno, Patrik Nagy, Pawel Szymczyk, PoAn Yang, Ken Huang, Ken Huang, Priyanka K U, Rajani K, Rajini Sivaram, Ram, Ritika Reddy, Robert Young, Ryan Dielhenn, S.Y. Wang, samarth-ksolves, Sanskar Jhajharia, Satish Duggana, Sean Quah, Sebastien Viale, Shang-Hao Yang, Shashank, Shivsundar R, ShivsundarR, Siyang He, Sophie Blee-Goldman, Stig Døssing, stroller, stroller.fu, Sushant Mahajan, TaiJuWu, TengYao Chi, Tsung-Han Ho (Miles Ho), Ubuntu, Uladzislau Blok, Vincent PÉRICART, Xiao Yang, xijiu, Xuan-Zhang Gong, yangxuze, Yeikel Santana, Yu-Syuan Jheng, YuChia Ma, Yunchi Pang, Yung

@brandboat, @m1a2st, Abhi Tiwari, Abhijeet Kumar, Abhinav Dixit, Abhiram98, Alex, Alieh Saeedi, ally heev, Alyssa Huang, Andrew J Schofield, Anton Vasanth, Apoorv Mittal, Arpit Goyal, Artem Livshits, Bill Bejeck, Bolin Lin, Bruno Cadonna, Calvin Liu, Chang-Chi Hsu, Chang-Yu Huang, Chia-Ping Tsai, Chih-Yuan Chien, Chirag Wadhwa, Chris Egerton, Christo Lolov, Chuckame, Clemens Hutter, Colin Patrick McCabe, d00791190, Dave Troiano, David Arthur, David Jacot, Deep Golani, Dejan Stojadinović, devtrace404, Dmitry Werner, Dongnuo Lyu, Donny Nadolny, Eduwer Camacaro, Elizabeth Bennett, EME, Eric Chang, Erik Anderson, Evan Zhou, Evanston Zhou, Evgeniy Kuvardin, farzan ghalami, Fatih, Federico Valeri, Gantigmaa Selenge, Gasparina Damien, Gaurav Narula, Genseric Ghiro, George Wu, Greg Harris, Harish Vishwanath, Herman Kolstad Jakobsen, Hong-Yi Chen, Ismael Juma, Izzy Harker, Jared Harley, Jhen-Yung Hsu, Jian, Jim Galasyn, jimmy, Jimmy Wang, Jing-Jia Hung, Jinhe Zhang, Joel Hamill, Jonah Hooper, Josep Prat, José Armando García Sancio, Juha Mynttinen, Jun Rao, Justine Olshan, k-apol, Kamal Chandraprakash, Kaushik Raina, keemsisi, Ken Huang, Kevin Wu, Kirk True, knoxy5467, KTKTK-HZ, Kuan-Po Tseng, Lan Ding, Levani Kokhreidze, Liam Clarke-Hutchinson, Lianet Magrans, Linsiyuan9, Logan Zhu, lorcan, Lord of Abyss, Lucas Brutschy, Lucy Liu, Luke Chen, Mahsa Seifikar, majialong, Manikumar Reddy, Maros Orsak, Masahiro Mori, Mason Chen, Matt Welch, Matthias J. Sax, Michael Knox, Michael Morris, Mickael Maison, Ming-Yen Chung, NeatGuyCoding, Nick Guo, NICOLAS GUYOMAR, Nikita Shupletsov, Now, Okada Haruki, Omnia Ibrahim, Otmar Ertl, OuO, Paolo Patierno, Patrik Nagy, Pawel Szymczyk, PoAn Yang, Ken Huang, Ken Huang, Priyanka K U, Rajani K, Rajini Sivaram, Ram, Ritika Reddy, Robert Young, Ryan Dielhenn, S.Y. Wang, samarth-ksolves, Sanskar Jhajharia, Satish Duggana, Sean Quah, Sebastien Viale, Shang-Hao Yang, Shashank, Shivsundar R, ShivsundarR, Siyang He, Sophie Blee-Goldman, Stig Døssing, stroller, stroller.fu, Sushant Mahajan, TaiJuWu, TengYao Chi, Tsung-Han Ho (Miles Ho), Ubuntu, Uladzislau Blok, Vincent PÉRICART, Xiao Yang, xijiu, Xuan-Zhang Gong, yangxuze, Yeikel Santana, Yu-Syuan Jheng, YuChia Ma, Yunchi Pang, Yung

Just removing some duplicates.

bbejeck@apache.org -> late in the list as Bill Bejeck

Matthias Sax -> previously in the list as Matthias J. Sax

updating lucliu1108 to real name Lucy Lui (she is from our team)

Liu not Lui ;)

Other duplicates

@brandboat, Kuan-Po Tseng

@m1a2st, Ken Huang also listed twice as Ken Huang

Shivsundar R, ShivsundarR

stroller, stroller.fu

Evan Zhou, Evanston Zhou

jimmy, Jimmy Wang

Make sure to adjust the count too

I removed the mentioned duplicates and adjusted the count 😊

Liu not Lui ;)

The diff is right. Just a typo on the comment.

stanislavkozlovski · 2026-01-20T08:36:19Z

Best descriptions of a feature release I've read so far. Really well written and exhaustive, thank you!

stanislavkozlovski · 2026-01-20T09:13:21Z

content/en/blog/releases/ak-4.2.0.md

+
+We are proud to announce the release of Apache Kafka® 4.2. This release contains many new features and improvements. This blog post will highlight some of the more prominent ones. For a full list of changes, be sure to check the [release notes](https://downloads.apache.org/kafka/4.2.0/RELEASE_NOTES.html).
+
+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.


worth including share.acquire.mode here? Seems useful.

side note - I was a little perplexed to see a new client-side option like that introduced for what was essentially a previous broker perf optimization (offset acquisition counting). I would have thought the new mode record_limit should have been the default, since it's a queue use case where jobs can in theory take minutes/hours too. I assume other users would think the same as me, hence I reason it's worthwhile to call this out

btw, adaptive batching is not only for Share Groups, right?

mjsax

Thanks. LGTM.

mjsax reviewed Jan 15, 2026

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Add 4.2 blog post

7f5016d

clolov force-pushed the 4_2_blog branch from 646efcd to 7f5016d Compare January 15, 2026 16:48

stanislavkozlovski reviewed Jan 20, 2026

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mjsax approved these changes Jan 20, 2026

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		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 gains dead letter queue support in exception handlers, anchored wall-clock punctuation for deterministic scheduling, and the new server-side rebalance protocol reaches GA with a limited feature set.

	Kafka Streams gains dead letter queue support in exception handlers, anchored wall-clock punctuation for deterministic scheduling, and the new server-side rebalance protocol reaches GA with a limited feature set.
	Kafka Streams gains the new server-side rebalance protocol reaches GA with a limited feature set, dead letter queue support in exception handlers, and anchored wall-clock punctuation for deterministic scheduling.


		We are proud to announce the release of Apache Kafka® 4.2. This release contains many new features and improvements. This blog post will highlight some of the more prominent ones. For a full list of changes, be sure to check the [release notes](https://downloads.apache.org/kafka/4.2.0/RELEASE_NOTES.html).

		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.

Add 4.2 blog post #786

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clolov commented Jan 14, 2026

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stanislavkozlovski commented Jan 20, 2026

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