How does consumer rebalancing work in Kafka?

Question

When a new consumer/brorker is added or goes down, Kafka triggers a rebalance operation. Is Kafka Rebalancing a blocking operation. Are Kafka consumers blocked while a rebal

Answer 1

The accepted response above (from serejja) was correct in the past. Kafka has implemented "Incremental Cooperative Rebalancing" from version 2.3 (release date June 2019) and above. So now there is no need for all consumers to stop the processing ("stop the world event") to rebalance work in group fe. when new consumer appears in group or some consumer goes offline.

For more info see: From Eager to Smarter in Apache Kafka Consumer Rebalances