Does changing the clientId will make Kafka to consider it as new consumer and perform rebalancing?

Question

I'm new to Kafka and exploring the Kafkajs documentation. I have a question regarding the clientId configuration. In the documentation, it's mentioned that the clientId is a logical grouping of clients with a meaningful name chosen by the client application.

My question is, if I change the clientId for a Kafka client(consuming messages) using Kafkajs, will the Kafka cluster consider it as a completely new consumer and perform rebalancing? How does Kafka handle changes in the clientId? Would appreciate any insights or best practices regarding managing clientId in Kafkajs.

I couldn't find answer.

Answer 1

In Kafka, the clientId functions as a logical grouping identifier for a Kafka client, serving to differentiate clients and manage their state within a consumer group. Altering the clientId for a Kafka consumer, which is responsible for message consumption, prompts Kafka to recognize it as a distinct and separate consumer. This change has the potential to trigger a rebalance within a consumer group, contingent on the consumer group management protocol in use—typically, employing the default combination of the Group Coordinator and Apache ZooKeeper.

Upon the inclusion of a consumer with a new clientId into a consumer group, Kafka initiates a rebalance to redistribute the partitions among all consumers in the group, including the newly introduced one. Throughout this rebalance process, partitions might be reassigned among different consumers to maintain an equitable distribution of workload.