[jira] [Commented] (BEAM-854) ReifyTimestampAndWindows explodes windows

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

    [ https://issues.apache.org/jira/browse/BEAM-854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15629814#comment-15629814 ] 

ASF GitHub Bot commented on BEAM-854:
-------------------------------------

Github user asfgit closed the pull request at:

    https://github.com/apache/incubator-beam/pull/1225


> ReifyTimestampAndWindows explodes windows
> -----------------------------------------
>
>                 Key: BEAM-854
>                 URL: https://issues.apache.org/jira/browse/BEAM-854
>             Project: Beam
>          Issue Type: Bug
>            Reporter: Eugene Kirpichov
>            Assignee: Kenneth Knowles
>
> Commit https://github.com/apache/incubator-beam/commit/b2350417f73ae6c34f849ff0e93d5bd93df3088d changed the fn from accessing the collection of windows to accessing the windows one-by-one, which causes this DoFn to explode them, which (I suppose) hurts performance, since this Fn is quite important: it's a part of GroupByKey in the Spark runner and Direct runner, part of Splittable DoFn, part of GBKViaGBKO, and part of GatherAllPanes.
> I can see a couple of ways to fix this:
> - Make this be a primitive transform, with runner-specific support to keep the windows compressed
> - Allow any DoFn to access the compressed representation explicitly using a Collection<BoundedWindow> parameter
> I'm personally in favor of the latter because it automatically benefits all runners.



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