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https://issues.apache.org/jira/browse/BEAM-4783?focusedWorklogId=144336&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-144336
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ASF GitHub Bot logged work on BEAM-4783:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 14/Sep/18 16:34
            Start Date: 14/Sep/18 16:34
    Worklog Time Spent: 10m 
      Work Description: lukecwik commented on issue #6181: [BEAM-4783] Add 
bundleSize for splitting BoundedSources.
URL: https://github.com/apache/beam/pull/6181#issuecomment-421414299
 
 
   I don't believe the Dataflow worker code is very useful for dynamic work 
rebalancing. Good dynamic work rebalancing will need support/signals from each 
runner. I believe there is a way to build simple dynamic work rebalancing 
system that would work for all bounded splits by performing a limited amount of 
graph rewriting at pipeline submission time and then periodic splitting while 
running sources. You need support for a self loop within the runner to be able 
to get support for unbounded soruces.

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

    Worklog Id:     (was: 144336)
    Time Spent: 2.5h  (was: 2h 20m)

> Spark SourceRDD Not Designed With Dynamic Allocation In Mind
> ------------------------------------------------------------
>
>                 Key: BEAM-4783
>                 URL: https://issues.apache.org/jira/browse/BEAM-4783
>             Project: Beam
>          Issue Type: Improvement
>          Components: runner-spark
>    Affects Versions: 2.5.0
>            Reporter: Kyle Winkelman
>            Assignee: Jean-Baptiste Onofré
>            Priority: Major
>              Labels: newbie
>          Time Spent: 2.5h
>  Remaining Estimate: 0h
>
> When the spark-runner is used along with the configuration 
> spark.dynamicAllocation.enabled=true the SourceRDD does not detect this. It 
> then falls back to the value calculated in this description:
>       // when running on YARN/SparkDeploy it's the result of max(totalCores, 
> 2).
>       // when running on Mesos it's 8.
>       // when running local it's the total number of cores (local = 1, 
> local[N] = N,
>       // local[*] = estimation of the machine's cores).
>       // ** the configuration "spark.default.parallelism" takes precedence 
> over all of the above **
> So in most cases this default is quite small. This is an issue when using a 
> very large input file as it will only get split in half.
> I believe that when Dynamic Allocation is enable the SourceRDD should use the 
> DEFAULT_BUNDLE_SIZE and possibly expose a SparkPipelineOptions that allows 
> you to change this DEFAULT_BUNDLE_SIZE.



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