Kafka Producer Batching : https://www.conduktor.io/kafka/kafka-producer-batching
A producer will have up to 5 requests in flight (controlled by the max.in.flight.requests.per.connection setting), meaning up to 5 message batches will be sent at the same time.
This smart batching allows Kafka to increase throughput while maintaining very low latency. Batches have a higher compression ratio so a better disk and networking efficiency. Batching is mainly controlled by two producer settings - linger.ms and batch.size.
The max size is represented by the setting “batch.size”. The default value of batch.size is 16 KB.