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https://issues.apache.org/jira/browse/FLINK-39990?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bowen Li reassigned FLINK-39990:
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Assignee: Bowen Li
> Expose DynamicKafkaSource.activeSplitCount metric per source reader
> -------------------------------------------------------------------
>
> Key: FLINK-39990
> URL: https://issues.apache.org/jira/browse/FLINK-39990
> Project: Flink
> Issue Type: New Feature
> Components: Connectors / Kafka
> Affects Versions: 2.3.0
> Reporter: Bowen Li
> Assignee: Bowen Li
> Priority: Major
> Fix For: 2.4.0
>
>
>
> {{DynamicKafkaSource should expose a per-reader/subtask metric named
> DynamicKafkaSource.activeSplitCount.
> The metric will be used by the Flink Kubernetes Operator autoscaler to detect
> when cluster/partition removal leaves empty subtasks or reduces the total
> active
> partition count below job parallelism.}}
> {{Metric semantics:}}
> * {{Gauge name: DynamicKafkaSource.activeSplitCount }}
> * {{Scope: per DynamicKafkaSource reader/subtask}}
> * {{Value: number of currently assigned active splits}}
> * {{Report 0 when no active splits are assigned}}
> * {{Retained removed partitions must not count toward this metric; they
> should
> retain offset/state only}}
>
> {{Autoscaler assumptions:}}
> - sum(activeSplitCount) < parallelism indicates the job should scale down
> - any subtask with activeSplitCount == 0 indicates the job should rebalance
> or restart
> Scope:
> This ticket only adds the source metric. Autoscaler behavior remains owned by
> the Flink Kubernetes Operator.
> Acceptance Criteria:
> - DynamicKafkaSource exposes activeSplitCount for every reader/subtask
> - Metric reports 0 before assignment and after all active splits are removed
> - Metric updates after split assignment, removal, and reactivation
> - Retained removed partitions are excluded from the count
> - Tests cover assignment, removal, empty reader, retained-state exclusion,
> and reactivation
> - Metrics documentation is updated
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