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https://issues.apache.org/jira/browse/BEAM-5063?focusedWorklogId=133573&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-133573
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ASF GitHub Bot logged work on BEAM-5063:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 10/Aug/18 13:02
            Start Date: 10/Aug/18 13:02
    Worklog Time Spent: 10m 
      Work Description: krzysztof-tr commented on issue #6178: [BEAM-5063] Fix 
Watermark does not progress for low traffic streams
URL: https://github.com/apache/beam/pull/6178#issuecomment-412075420
 
 
   @iemejia, Could you take a look at the changes and merge them if they are ok 
with you?

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Issue Time Tracking
-------------------

    Worklog Id:     (was: 133573)
    Time Spent: 40m  (was: 0.5h)

> Watermark does not progress for low traffic streams
> ---------------------------------------------------
>
>                 Key: BEAM-5063
>                 URL: https://issues.apache.org/jira/browse/BEAM-5063
>             Project: Beam
>          Issue Type: Bug
>          Components: io-java-kinesis
>    Affects Versions: 2.5.0
>            Reporter: Krzysztof Trubalski
>            Assignee: Jean-Baptiste Onofré
>            Priority: Major
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> We have a Dataflow Job copying data from multiple Kinesis streams into Big 
> Query. Recently we have noticed that the watermark on one of the streams 
> frequently gets stuck although data from that stream is still being processed 
> (it progress only when the traffic increases or Dataflow autoscaling feature 
> kicks in).
>   
>  Looking at the CloudWatch statistics for the affected stream, it has a 
> really low traffic rate - only ~1 event every few minutes . After 
> investigation and consulting the issue with Google's Dataflow Team, it looks 
> like with such small amount of data on the stream, the function calculating 
> the watermark in KinesisReader reports progress incorrectly.
>   
>  From my initial investigation, I suspect that the issue might be related to 
> usage of MovingFunction in KinesisReader. In the current implementation, it 
> covers 1 minute period of samples, since obtaining the min value flushes 
> stale values, if the traffic is very low the following call to significance 
> check always returns false (as it relies on the number of samples, and most 
> of them were flushed by get() invocation).
>   
>   
>   



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