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https://issues.apache.org/jira/browse/BEAM-958?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Raghu Angadi updated BEAM-958:
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Labels: breaking_change (was: )
> desiredNumWorkers in Dataflow is too low
> ----------------------------------------
>
> Key: BEAM-958
> URL: https://issues.apache.org/jira/browse/BEAM-958
> Project: Beam
> Issue Type: Improvement
> Components: runner-dataflow
> Affects Versions: 0.3.0-incubating
> Reporter: Raghu Angadi
> Assignee: Davor Bonaci
> Labels: breaking_change
>
> {{desiredNumWorkers}} in [UnboundedSource
> API|https://github.com/apache/incubator-beam/blob/v0.3.0-incubating-RC1/sdks/java/core/src/main/java/org/apache/beam/sdk/io/UnboundedSource.java#L69]
> is a suggestion to a source about how many splits it should create. KafkaIO
> currently takes this literally and only creates up to this many splits.
> The main draw back is that it is very low in Dataflow. It is calculated as
> * {{1 * maxNumWorkers}} if {{--maxNumWorkers}} is specified, otherwise
> * {{3 * numWorkers}}.
> That implies there is only single reader per worker (which is usually a 4
> core VM). That can leave CPU under utilized on many pipelines.
> Even 3x in case of fixes number of workers seems low to me.
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