[jira] [Commented] (KAFKA-9175) MirrorMaker 2 emits invalid topic partition metrics

["Ryanne Dolan (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-9175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16973597#comment-16973597 ] 

Ryanne Dolan commented on KAFKA-9175:
-------------------------------------

Thanks [~ecomar], [~mimaison], lgtm.

> MirrorMaker 2 emits invalid topic partition metrics
> ---------------------------------------------------
>
>                 Key: KAFKA-9175
>                 URL: https://issues.apache.org/jira/browse/KAFKA-9175
>             Project: Kafka
>          Issue Type: Bug
>          Components: KafkaConnect
>    Affects Versions: 2.4.0
>            Reporter: Mickael Maison
>            Assignee: Mickael Maison
>            Priority: Blocker
>         Attachments: image-2019-11-12-17-42-45-773.png
>
>
> While looking at MirrorMaker 2 metrics with [~ecomar], we noticed the topic partition metrics were invalid. 
>  !image-2019-11-12-17-42-45-773.png|width=822,height=615!
> There is no traffic on the topic spp.hello but its metrics are constantly updating.
> The issue is in {{MirrorMetrics.PartitionMetrics}}. In the constructor, Sensors are built using {{metrics.sensor()}} with a name that does not include the topic partition. The method {{metrics.sensor()}} does not always create a new Sensor but can return an existing Sensor if one exists for the specified name. So in practice, if a Task is handling many topic partitions, they all share the same Sensors!
> This renders the topic partition metrics unusable and really prevents running MirrorMaker 2 in a production environment.



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