[jira] [Updated] (KAFKA-12718) SessionWindows are closed too early

["Matthias J. Sax (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-12718?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Matthias J. Sax updated KAFKA-12718:
------------------------------------
    Labels: beginner easy-fix newbie  (was: )

> 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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