This 101st edition of the Kafka Monthly Digest covers what happened in the Apache Kafka community in June 2026.
For last month’s digest, see Kafka Monthly Digest: May 2026.
Releases
There is one new release, 4.3.1, and 4.4.0 is in progress:
4.3.1
After 3 release candidates, Bill Bejeck released 4.3.1 on June 25. This bug fix release fixes 16 issues, including a fix for a significant memory leak in Kafka Streams. You can find the announcement on the blog and the release plan in the wiki.
4.4.0
The community adjusted the expected release date for Kafka 4.4.0 to September. The next milestone is KIP freeze on July 8. You can find the release plan in the wiki.
Kafka Improvement Proposals
Last month, the community submitted 5 KIPs (KIP-1356 to KIP-1360). I'll highlight a few of them:
KIP-1357: Add broker side custom assignors for "streams" groups: Since Kafka 4.2.0, Streams can use the new server-side rebalance protocol (KIP-1071). One limitation of this new model is that users can't bring their own customized assignors anymore. This KIP targets this limitation by making the server-side assignor customizable so users that add their own assignors can easily migrate to the new model.
KIP-1358: Gradual and gated preferred-leader election in the KRaft controller: This KIP aims at softening the impact of preferred leader elections when a broker rejoins the cluster. At the moment, elections happen every
leader.imbalance.check.interval.seconds(5 mins by default) but each run can trigger 1000s of elections at the same time and visibly affect latencies. This KIP would introduce new configurations to tune how elections are triggered.
KIP-1360: Cluster Synchronous Mirroring: This KIP builds on top of KIP-1279 and proposes supporting synchronous mirroring. Synchronous mirroring means that a record would only be considered received when all ISR on all mirror clusters have successfully received it. This would enable cluster mirroring to support new use cases such as zero RPO disaster recovery, and easier migration of Kafka Connect and Streams deployments.
Community Releases
I selected releases of some open source community projects:
strimzi-kafka-operator 1.1.0: Strimzi is a Kubernetes Operator for running Kafka. This adds support for Kafka 4.3.0 and 4.2.1. It adds a new listener type
tlsroutebased on the Kubernetes Gateway API. KafkaBridge and KafkaMirrorMaker2 now use PEM files instead of P12/JKS for TLS.
Blogs
I selected some interesting blog articles that were published last month:
- Kafka Share Groups - Pathological fetch waits with record_limit
- Kafka is easier to understand when you can break it
- Kafka Failures Aren’t Random — They’re Architectural
To learn more about Kafka, visit Red Hat Developer's Apache Kafka topic page.
