Concurrency and Thread Management

When consuming messages from Kafka, processing them sequentially might not be fast enough. Concurrency allows your application to process multiple messages in parallel, significantly increasing throughput.

This is crucial for high-volume topics where messages arrive rapidly and need quick processing.

By default, a @KafkaListener method in Spring Boot will create one consumer thread per listener container. This single thread is responsible for fetching and processing messages from the partitions assigned to it.

While simple, this setup doesn't always leverage multi-core processors for parallel message processing from a single topic effectively.