A Kafka administrator notices that their consumers of Topic X are starting to fall behind.

Kafka consumers in a consumer group consume partitions exclusively. With 4 partitions and only 2 consumers, each consumer is processing 2 partitions. To increase parallelism, more consumers can be added to the group (up to 4) so that each consumer handles fewer partitions, which reduces the lag.

From Kafka documentation:

“Increasing the number of consumers in a group increases parallelism and helps reduce lag, assuming there are enough partitions.”

A → Ineffective unless followed by rebalancing and consumer scaling.

B → Would create a separate group and not share load.

C → Not applicable; consumers don’t acknowledge messages like producers.

Page Reference:

Kafka: The Definitive Guide, 1st Edition, Chapter 4, p. 127–129

Apache Kafka Documentation: Consumer Group Behavior

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾