Symptoms
In the ApsaraMQ for Kafka console, the consumer information is displayed as n/a in the Client column on the Subscriptions tab of the Topic Details page or the Consumer Status tab of the Group Details page. 
Causes
- The consumption thread that subscribes to a specific topic partition is offline.
- The consumer group triggers the Rebalance policy. During the rebalancing process, all consumption threads of the consumer group stop the consumption.
- You use the
assignmode to manually specify a consumer to consume the messages in a specific partition. The subscription is defined, but open source Kafka does not record the subscription. The consumer information is displayed in the console only if you use thesubscribemode to automatically assign different partitions to consumers.