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https://issues.apache.org/jira/browse/KAFKA-12718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17336997#comment-17336997
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A. Sophie Blee-Goldman commented on KAFKA-12718:
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{quote}I was just looking into `suppress()` implementation, that obviously does
not know anything about semantics of upstream window definitions{quote}
[~mjsax] can you elaborate? Suppression does in fact search the processor graph
to find the grace period of the windowed operator which is upstream of the
suppression. It's called GraphGraceSearchUtil or something
> SessionWindows are closed too early
> -----------------------------------
>
> Key: KAFKA-12718
> URL: https://issues.apache.org/jira/browse/KAFKA-12718
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Matthias J. Sax
> Priority: Major
> Labels: beginner, easy-fix, newbie
> Fix For: 3.0.0
>
>
> SessionWindows are defined based on a {{gap}} parameter, and also support an
> additional {{grace-period}} configuration to handle out-of-order data.
> To incorporate the session-gap a session window should only be closed at
> {{window-end + gap}} and to incorporate grace-period, the close time should
> be pushed out further to {{window-end + gap + grace}}.
> However, atm we compute the window close time as {{window-end + grace}}
> omitting the {{gap}} parameter.
> Because default grace-period is 24h most users might not notice this issues.
> Even if they set a grace period explicitly (eg, when using suppress()), they
> would most likely set a grace-period larger than gap-time not hitting the
> issue (or maybe only realize it when inspecting the behavior closely).
> However, if a user wants to disable the grace-period and sets it to zero (on
> any other value smaller than gap-time), sessions might be close too early and
> user might notice.
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