Current state: "Under Discussion"
Discussion thread: here
Voting thread: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
As owner of Kafka cluster, but not the owner of clients, I am not capable of telling which topics/partitions are being actively read from (= have running clients that are sending fetch requests).
The existing metric kafka.server:type=BrokerTopicMetrics,name=TotalFetchRequestsPerSec,topic=topic aggregates both fetch requests made by clients and replicas.
So for partitions with replication factor > 1, even if the partition is no longer read from by clients, the above metric is still growing due to requests made by replicas.
The following new broker-side metric is proposed:
It would be similar to the already-existing TotalFetchRequestsPerSec metric.
These are new metrics and there should be no impact on existing users.