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https://issues.apache.org/jira/browse/FLINK-11912?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17323339#comment-17323339
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Flink Jira Bot commented on FLINK-11912:
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This issue is assigned but has not received an update in 7 days so it has been
labeled "stale-assigned". If you are still working on the issue, please give an
update and remove the label. If you are no longer working on the issue, please
unassign so someone else may work on it. In 7 days the issue will be
automatically unassigned.
> Expose per partition Kafka lag metric in Flink Kafka connector
> --------------------------------------------------------------
>
> Key: FLINK-11912
> URL: https://issues.apache.org/jira/browse/FLINK-11912
> Project: Flink
> Issue Type: New Feature
> Components: Connectors / Kafka
> Affects Versions: 1.6.4, 1.7.2
> Reporter: Shuyi Chen
> Assignee: Shuyi Chen
> Priority: Major
> Labels: stale-assigned
>
> In production, it's important that we expose the Kafka lag by partition
> metric in order for users to diagnose which Kafka partition is lagging.
> However, although the Kafka lag by partition metrics are available in
> KafkaConsumer after 0.10.2, Flink was not able to properly register it
> because the metrics are only available after the consumer start polling data
> from partitions. I would suggest the following fix:
> 1) In KafkaConsumerThread.run(), allocate a manualRegisteredMetricSet.
> 2) in the fetch loop, as KafkaConsumer discovers new partitions, manually add
> MetricName for those partitions that we want to register into
> manualRegisteredMetricSet.
> 3) in the fetch loop, check if manualRegisteredMetricSet is empty. If not,
> try to search for the metrics available in KafkaConsumer, and if found,
> register it and remove the entry from manualRegisteredMetricSet.
> The overhead of the above approach is bounded and only incur when discovering
> new partitions, and registration is done once the KafkaConsumer have the
> metrics exposed.
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