Why Is the Number of Stacked Messages Monitored as 0 when Messages Are Stacked?

Symptom

On the Consumer Offset tab page of the consumer group details page, the total number of stacked messages is not 0. However, the Accumulated Messages (Consumer Available Messages) is 0 on the consumer group monitoring page.

Conclusion

These metrics are not synchronously updated.

The metric on the Consumer Offset tab page is sampled immediately. The metric on the consumer group monitoring page is sampled every minute. You see the stack number at your time. When a consumer consumes all the stacked messages within 1 minute, Accumulated Messages (Consumer Available Messages) displays 0.