sjhajharia commented on code in PR #668:
URL: https://github.com/apache/kafka-site/pull/668#discussion_r1993107835
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blog.html:
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@@ -22,6 +22,286 @@
<!--#include virtual="includes/_nav.htm" -->
<div class="right">
<h1 class="content-title">Blog</h1>
+ <article>
+ <h2 class="bullet">
+ <a id="apache_kafka_400_release_announcement"></a>
+ <a href="#apache_kafka_400_release_announcement">Apache
Kafka 4.0.0 Release Announcement</a>
+ </h2>
+ 17 March 2025 - David Jacot
+
+ <p>
+ We are proud to announce the release of Apache Kafka®
4.0 This release contains many new
+ features and improvements. This blog post will highlight
some of the more prominent features.
+ For a full list of changes, be sure to check the <a
href="https://archive.apache.org/dist/kafka/4.0.0/RELEASE_NOTES.html";>release
notes</a>.
+ </p>
+ <p>
+ Apache Kafka 4.0 is a significant milestone, marking the
first major release to operate entirely
+ without Apache ZooKeeper®. By running in KRaft mode
by default, Kafka simplifies
+ deployment and management, eliminating the complexity of
maintaining a separate ZooKeeper
+ ensemble. This change significantly reduces operational
overhead, enhances scalability, and
+ streamlines administrative tasks. We want to take this as
an opportunity to express our gratitude
+ to the ZooKeeper community and say, thank you! ZooKeeper
was the backbone of Kafka for
+ more than 10 years, and it did serve Kafka very well.
Kafka would most likely not be what it is
+ today without it. We don’t take this for granted and
highly appreciate all the hard work the
+ community invested to build ZooKeeper. Thank you!
+ </p>
+ <p>
+ Kafka 4.0 also brings the general availability of <a
href="https://cwiki.apache.org/confluence/x/HhD1D";>KIP-848</a> introducing a
powerful new consumer
+ group protocol designed to dramatically improve rebalance
performance. This optimization
+ significantly reduces downtime and latency, enhancing the
reliability and responsiveness of
+ consumer groups, especially in large-scale deployments.
+ </p>
+ <p>
+ Additionally, we are excited to offer <a
href="https://cwiki.apache.org/confluence/x/i4ogF";>early access</a> to
+ Queues for Kafka (<a
href="https://cwiki.apache.org/confluence/x/4hA0Dw";>KIP-932</a>), enabling
Kafka to support traditional queue semantics directly. This
+ feature extends Kafka’s versatility, making it an ideal
messaging platform for a wider range of
+ use cases, particularly those requiring point-to-point
messaging patterns.
+ </p>
+ <p>
+ Kafka's major releases, such as version 4.0, remove APIs
deprecated for at least 12 months to simplify the platform
+ and encourage the adoption of newer features. Notably, in
Kafka 4.0, Kafka Clients and Kafka Streams require Java 11,
+ while Kafka Brokers, Connect, and Tools now require Java
17. This release also updated the minimum supported client
+ and broker versions (<a
href="https://cwiki.apache.org/confluence/x/K5sODg";>KIP-896</a>) and defined
new baseline
+ requirements for supported upgrade paths. Further details
are provided in subsequent sections of this document.
+ </p>
+ <p>
+ These highlights illustrate Kafka's continued evolution to
meet the demands of modern,
+ scalable, and efficient data streaming and messaging
architectures.
+ </p>
+ <p>
+ See the <a
href="https://kafka.apache.org/documentation.html#upgrade_4_0_0";>Upgrading to
4.0</a> section in the
+ documentation for the list of notable changes and detailed
upgrade steps.
+ </p>
+
+ <h3>Kafka Broker, Controller, Producer, Consumer and Admin
Client</h3>
+
+ <ul>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/HhD1D";>KIP-848: The Next Generation
of the Consumer Rebalance Protocol</a>
+ <br>
+ Apache Kafka also says goodbye to “stop-the-world”
rebalances with the general availability of the
+ next generation of the consumer rebalance protocol. It
increases the stability and the performance
+ of consumer groups while simplifying clients. The new
protocol is enabled by default on the server
+ side. Consumers must opt-in by setting
<code>group.protocol=consumer</code>.
+ See <a
href="https://kafka.apache.org/40/documentation.html#consumer_rebalance_protocol";>here</a>
for details.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/B40ODg";>KIP-890: Transactions
Server-Side Defense</a>
+ <br>
+ The second phase of KIP-890 has been completed. It
reduces the chances of “zombie transactions”
+ during producer failures. See <a
href="https://kafka.apache.org/40/documentation.html#transaction_protocol";>here</a>
for details.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/4hA0Dw";>KIP-932: Queues for Kafka
(Early Access)</a>
+ <br>
+ This KIP introduces the concept of a share group as a
way of enabling cooperative consumption
+ using Kafka topics. It does not add the concept of a
“queue” to Kafka per se, but rather that
+ introduces cooperative consumption to accommodate
these queuing use-cases using regular Kafka
+ topics. Share groups make this possible. You can think
of a share group as roughly equivalent to a
+ “durable shared subscription” in existing systems.
+ Please see the <a
href="https://cwiki.apache.org/confluence/x/i4ogF";>Early Access Release
Notes</a>
+ for limitations and configurations.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/mpOzDw";>KIP-966: Eligible Leader
Replicas (Preview)</a>
+ <br>
+ KIP-966 introduces Eligible Leader Replicas (ELR) in
preview in 4.0. ELR is a subset of the ISR
+ replicas guaranteed to have complete data up to the
high-watermark. ELRs are safe for leader
+ election, preventing data loss. See <a
href="https://kafka.apache.org/40/documentation.html#eligible_leader_replicas";>here</a>
for details.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/MYtEE";>KIP-996: Pre-Vote</a>
+ <br>
+ KIP-996 introduces a "Pre-Vote" mechanism to reduce
unnecessary KRaft leader elections in Apache
+ Kafka clusters. By allowing nodes to check their
eligibility for leadership before initiating an election,
+ this approach minimizes disruptions caused by network
partitions or transient issues.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/XA-OEg";>KIP-1076: Metrics for
client applications KIP-714 extension</a>
+ <br>
+ With <a
href="https://cwiki.apache.org/confluence/x/XA-OEg";>KIP-714</a>, cluster
operators can now collect
+ client metrics directly from brokers using a plugin.
This makes it much easier to monitor client behavior.
+ However, KIP-714 only gathers metrics from Kafka
clients (admin, consumer, and producer) and doesn't cover
+ application-level metrics for embedded clients, such
as Kafka Streams. To fully understand performance,
+ it's important to collect both client metrics and
application-specific metrics. This KIP introduces a way
+ for applications that use Kafka clients to include
their own metrics alongside the existing client metrics.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/NIyMEw";>KIP-1106: Add duration
based offset reset option for consumer clients</a>
+ <br>
+ Kafka consumer supports <code>auto.offset.reset</code>
config option, which is used when there is no initial
+ offset in Kafka or if the current offset does not
exist any more on the server. This config currently
+ supports earliest/latest/none options. Currently
consumer resets might force applications to
+ reprocess large amounts of data from earlier offsets.
With infinite storage, it's beneficial to have a
+ duration based offset reset strategy. This KIP allows
applications to consume/initialise from a fixed
+ duration when there is no initial offset in Kafka.
+ </li>
+ <li>
+ <a
href="https://cwiki.apache.org/confluence/x/XoowEg";>KIP-1043: Administration of
groups</a>
+ <br>
+ KIP-848 and KIP-932 introduce new group types,
consumer and share respectively. The Admin Client
+ API has limitations when dealing with newer group
types, sometimes returning errors or incorrectly
+ stating that groups don't exist. To address this
challenge, a new command-line tool, kafka-groups.sh,
Review Comment:
Suggestion:
`<code>kafka-groups.sh</code>`
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