Symptoms

A consumer group does not appear in the Message Queue for Apache Kafka console. However, consumer threads in this consumer group are consuming messages.

Causes

  • A consumer uses the assign mode to consume messages. In this case, consumer threads may be able to consume messages even if you do not create a consumer group.
  • A consumer uses the subscribe mode to consume messages. After the related consumer group is deleted, consumer threads can continue to consume messages in the case that the consumer threads are not stopped or rebalancing is not triggered.
  • Auto creation of consumer groups is enabled for your Message Queue for Apache Kafka instance. In this case, consumer threads can consume messages even if you do not create a consumer group.

Solutions

  • If a consumer uses the assign mode to consume messages, or auto creation of consumer groups is enabled for your Message Queue for Apache Kafka instance, create a consumer group in the Message Queue for Apache Kafka console in advance.
    Use existing consumer groups as much as possible, because the cluster stability may be affected if the number of created consumer groups exceeds the limit on the consumer group count. For more information about the limit on the consumer group count, see Limits.
  • Before you delete a consumer group, make sure that all consumer threads in the consumer group are stopped.
    Note If you receive a message accumulation alert for a consumer group that does not appear in the console, troubleshoot the issue by following the instructions provided in Why did I receive a message accumulation alert after I deleted the consumer group?