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From "Kenneth Knowles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (BEAM-1316) DoFn#startBundle and #finishBundle should not be able to output
Date Thu, 26 Jan 2017 19:57:24 GMT

    [ https://issues.apache.org/jira/browse/BEAM-1316?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15840324#comment-15840324
] 

Kenneth Knowles commented on BEAM-1316:
---------------------------------------

That is a good example that breaks my false dichotomy.

I think between BEAM-1283 and BEAM-1287 there can be a coherent solution. But even with all
the planned changes if you want decently windowed output you'll end up tracking it yourself,
unless we introduce per-window finishBundle/flush (which was frowned upon some time ago, but
maybe makes sense here).

> DoFn#startBundle and #finishBundle should not be able to output
> ---------------------------------------------------------------
>
>                 Key: BEAM-1316
>                 URL: https://issues.apache.org/jira/browse/BEAM-1316
>             Project: Beam
>          Issue Type: Bug
>          Components: sdk-java-core
>            Reporter: Thomas Groh
>
> While within startBundle and finishBundle, the window in which elements are output is
not generally defined. Elements must always be output from within a windowed context, or the
{{WindowFn}} used by the {{PCollection}} may not operate appropriately.
> startBundle and finishBundle are suitable for operational duties, similarly to {{setup}}
and {{teardown}}, but within the scope of some collection of input elements. This includes
actions such as clearing field state within a DoFn and ensuring all live RPCs complete successfully
before committing inputs.



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