[jira] [Commented] (FLINK-9789) Watermark metrics for an operator&task shadow each other

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-9789?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16538446#comment-16538446 ] 

ASF GitHub Bot commented on FLINK-9789:
---------------------------------------

GitHub user zentol opened a pull request:

    https://github.com/apache/flink/pull/6292

    [FLINK-9789][metrics] Ensure uniqueness of watermark metrics

    ## What is the purpose of the change
    
    This PR ensures that all registered watermark metric objects are only registered once; shared gauges must be wrapped and registered separately to avoid collisions in reporters which generally assume that metric objects are unique.
    
    ## Brief change log
    
    * ensure uniqueness by wrapping re-used metrics in `[One|Two]InputStreamTask` and `OperatorChain`
    * add `InterceptingTaskMetricGroup` to gather registered metrics
    * modify `[One|Two]InputStreamTask#testWatermarkMetrics` to check uniqueness of registered objects, and cover re-use for tasks
    
    ## Verifying this change
    
    * run `[One|Two]InputStreamTask#testWatermarkMetrics`
    * run any streaming job and check existence of all watermark metrics for task and operator
      * (via REST API: /job/<job_id>/vertices/<vertex_id>/metrics)
      * see the [metrics documentation](https://ci.apache.org/projects/flink/flink-docs-master/monitoring/metrics.html#io) for a list of expected metrics


You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/zentol/flink 9789

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/6292.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #6292
    
----
commit 4a7a0c6114893250e625dc36d953209de22ce57e
Author: zentol <ch...@...>
Date:   2018-07-10T11:27:34Z

    [FLINK-9789][metrics] Ensure uniqueness of watermark metrics

----


> Watermark metrics for an operator&task shadow each other
> --------------------------------------------------------
>
>                 Key: FLINK-9789
>                 URL: https://issues.apache.org/jira/browse/FLINK-9789
>             Project: Flink
>          Issue Type: Bug
>          Components: Metrics
>    Affects Versions: 1.5.0, 1.6.0
>            Reporter: Chesnay Schepler
>            Assignee: Chesnay Schepler
>            Priority: Blocker
>              Labels: pull-request-available
>             Fix For: 1.5.2, 1.6.0
>
>
> In FLINK-4812 we reworked the watermark metrics to be exposed for each operator.
> In FLINK-9467 we made further modifications to also expose these metrics again for tasks.
> In both JIRAs we register a single metric multiple times, for example the input watermark metric is registered for both the first operator in the task, and the task itself.
> Unfortunately, the metric system assumes metric objects to be unique, as can be seen in virtually all reporter implementations as well as the MetricQueryService.
> As a result the watermark metrics override each other in the reporter, causing only one to be reported, whichever was registered last.



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