Current state: Accepted
Discussion thread: here
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Currently, we have the following metrics per broker.
The issue is that the former accounts for traffic from the producer client, but the latter accounts for traffic from the consumer client as well as internal replication. This inconsistency can be confusing. The same issue exists for the same metric at the topic level.
The proposal is to make the metrics more consistent. First, the existing metric kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec will be changed to only account for traffic from the consumer. The same change applies to the BytesOutPerSec metric at the topic level too. Two new metrics kafka.server:type=BrokerTopicMetrics,name=ReplicationBytesInPerSec and kafka.server:type=BrokerTopicMetrics,name=ReplicationBytesOutPerSec will be added to account for incoming/outgoing traffic due to internal replication. The new metrics won't be at the topic level.
Compatibility, Deprecation, and Migration Plan
Users who are tracking the BytesOutPerSec metric will need to understand that the meaning of the value has changed.