Status

Current state: "Under Discussion"

Discussion thread: here

JIRA: here

Motivation

The metrics were originally named using the `kafka.<COMPONENT>` format. However, an unexpected name was introduced during the initialization of a metric in this patch.

Subsequent developers were unaware of this change and began using the new package-based naming as the metricName. In reality, the correct convention should adhere to the original kafka.<COMPONENT> format.

This KIP proposes to standardize Kafka metric naming by updating the `org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool` metric to follow the consistent kafka.<COMPONENT> naming convention used across other Kafka metrics.

Public Interfaces

• org.apache.kafka.storage.internals.log.RemoteStorageThreadPool 
• org.apache.kafka.server.log.remote.storage.RemoteStorageMetrics 

Proposed Changes

Introduce a new metric: kafka.server:type=AssignmentsManager, consistent with other Kafka metrics.

This change will impact external monitoring systems that rely on the old metric name; corresponding updates will be required.

Deprecate the following metrics

• org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool.RemoteLogReaderTaskQueueSize
• org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent

Introduce following new metric: 

• kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent
• kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderTaskQueueSize

This change will impact external monitoring systems that rely on the old metric name; corresponding updates will be required.

Compatibility, Deprecation, and Migration Plan

1. We will add a deprecated annotation on `RemoteStorageMetrics#REMOTE_LOG_READER_TASK_QUEUE_SIZE_METRIC` and `RemoteStorageMetrics#REMOTE_LOG_READER_AVG_IDLE_PERCENT_METRIC`
2. Update the Kafka documentation to note MBean will be replaced
   1. org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool.RemoteLogReaderTaskQueueSize
   2. org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent
3. Register new metrics `kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderTaskQueueSize` and `kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent` into `RemoteStorageThreadPool#metricsGroup`
4. Delete `RemoteStorageMetrics#REMOTE_LOG_READER_TASK_QUEUE_SIZE_METRIC` and `RemoteStorageMetrics#REMOTE_LOG_READER_AVG_IDLE_PERCENT_METRIC all usage in code base.

Test Plan

• Add new tests to verify the new metric is correctly registered and behaves as expected.
• Ensure backward compatibility by verifying deprecated metric behavior until removal.

Rejected Alternatives

n/a