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Table of Contents

Status

Current state: "Under DiscussionAccepted"

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: KAFKA-17876 

Motivation

The metrics were originally named `kafka.<COMPONENT>`, but they were unexpectedly changed when ew move Java classes from `kafka.server` to the server module in this (commit)[https://github.com/apache/kafka/commit/df78204e05bb1c416d977a0a36f4c263251ae4ef#diff-16a3a4c37cd87960638de8160b1969a0df76f1c0322c4af026bd2b9802777cbeL18]
Subsequent developers didn’t notice this change and used the new package name as the metricName. The correct naming should actually be reverted to kafka.<COMPONENT>.

...


Vote thread: here

JIRA:

Jira
serverASF JIRA
columnIdsissuekey,summary,issuetype,created,updated,duedate,assignee,reporter,customfield_12311032,customfield_12311037,customfield_12311022,customfield_12311027,priority,status,resolution
columnskey,summary,type,created,updated,due,assignee,reporter,Priority,Priority,Priority,Priority,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyKAFKA-17876
Jira
serverASF JIRA
columnIdsissuekey,summary,issuetype,created,updated,duedate,assignee,reporter,customfield_12311032,customfield_12311037,customfield_12311022,customfield_12311027,priority,status,resolution
columnskey,summary,type,created,updated,due,assignee,reporter,Priority,Priority,Priority,Priority,priority,status,resolution
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyKAFKA-19150

Motivation

Kafka metrics have traditionally followed a consistent naming convention using the kafka.<COMPONENT> format. However, some inconsistencies were unintentionally introduced during recent refactorings:

  • The metrics under org.apache.kafka.server:type=AssignmentsManager were originally named using the kafka.<COMPONENT> format. This changed unexpectedly when classes were moved from the kafka.server package to org.apache.kafka.server as part of this commit.
  • Similarly, the org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool metric was initially intended to follow the same convention. However, an incorrect metric name was introduced during initialization in a later patch.

These changes went unnoticed, and subsequent users began using the new org.apache.kafka.<COMPONENT> pattern, diverging from the established convention.

This KIP proposes to standardize Kafka metric naming by reverting the following metrics to the correct kafka.<COMPONENT> format to ensure consistency across the system:

  • org.apache.kafka.server:type=AssignmentsManager

...

  • → kafka.server:type=AssignmentsManager

  • org.apache.kafka.storage.internals.log:type=RemoteStorageThreadPool → kafka.log.remote:type=RemoteStorageThreadPool

This change will align these metrics with the broader Kafka metrics ecosystem and avoid confusion for users and tooling that rely on consistent naming.

Public Interface

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

...

  • org.apache.kafka.server.AssignmentsManager

Proposed Changes

...

Introduce new metrics, 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
  • org.apache.kafka.server:type=AssignmentsManager

...

  • .QueuedReplicaToDirAssignments

Introduce following new metric: 

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

...

  • .

...

  • QueuedReplicaToDirAssignments

This

...

change

...

will

...

impact

...

external

...

monitoring

...

systems

...

that

...

rely

...

on

...

the old metric name; corresponding updates will be required.

Due to 

Compatibility, Deprecation, and Migration Plan

...

  1. We will add a deprecated annotation on following constant
    1. `RemoteStorageMetrics#REMOTE_LOG_READER_TASK_QUEUE_SIZE_METRIC`
    2. `RemoteStorageMetrics#REMOTE_LOG_READER_AVG_IDLE_PERCENT_METRIC`
    3. `AssignmentsManager#QUEUED_REPLICA_TO_DIR_ASSIGNMENTS_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.

...

    1. storage.internals.log:type=

...

    1. RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent`
    2. `org.apache.kafka.server:type=AssignmentsManager

...

    1. .QueuedReplicaToDirAssignments`
  2. Register folowing new metrics
    1. `kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderTaskQueueSize`
    2. `kafka.log.remote:type=RemoteStorageThreadPool.RemoteLogReaderAvgIdlePercent`
    3. `kafka.server:type=AssignmentsManager

...

    1. .QueuedReplicaToDirAssignments`
  2. Delete following all usage in code base at the Kafka 5.0
    1. `RemoteStorageMetrics#REMOTE_LOG_READER_TASK_QUEUE_SIZE_METRIC`
    2. `RemoteStorageMetrics#REMOTE_LOG_READER_AVG_IDLE_PERCENT_METRIC`
    3. `AssignmentsManager#QUEUED_REPLICA_TO_DIR_ASSIGNMENTS_METRIC`

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.

Test Plan

...

Rejected Alternatives

n/a