A new major version of the KafkaConsumer is out, bringing in fundamental changes and improvements, as it’s the first version to fully implement the next generation of the Consumer Group Rebalance Protocol, introduced with KIP-848. It’s all a brand new production-ready feature now! Want to hear about how these major changes materialize in the KafkaConsumer? What’s in? What’s out? What’s different? This talk is for you then! We will cover the core of the new rebalance protocol, its implementation on the Java client, and how it significantly improves and simplifies the whole group consumption experience, addressing its main pain points. We will also share about the revamped KafkaConsumer threading model, shipped alongside the new rebalance protocol client implementation. It all sounds promising, but we do know that upgrades might be scary, right? Whether you’re a Kafka developer, operator, or architect, this talk will equip you with everything you need to confidently adopt KafkaConsumer 4.0 in your client applications. From how the live upgrade and protocol interoperability works, to detailed client changes: configuration changes, API deprecations and additions, improved API behavior, new metrics…