Explain the concept of consumer groups in Apache Kafka and their role

In Apache Kafka, a consumer group is a set of one or more consumers that jointly read data from topics. Each consumer in the group gets a unique set of topic partitions, allowing messages to be processed in parallel without duplication.

Roles of consumer groups:

• Scaling processing: multiple consumers in a group can read different partitions in parallel.
• Ensuring fault tolerance: if one consumer fails, its partitions are redistributed among the remaining consumers.
• Guaranteeing unique processing: each message is processed by only one consumer in the group.

Example: if a topic has 4 partitions and the group consists of 2 consumers, each will get 2 partitions to read.