[jira] [Resolved] (KAFKA-8924) Default grace period (-1) of TimeWindows causes suppress to emit events after 24h

["A. Sophie Blee-Goldman (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-8924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

A. Sophie Blee-Goldman resolved KAFKA-8924.
-------------------------------------------
    Resolution: Duplicate

> Default grace period (-1) of TimeWindows causes suppress to emit events after 24h
> ---------------------------------------------------------------------------------
>
>                 Key: KAFKA-8924
>                 URL: https://issues.apache.org/jira/browse/KAFKA-8924
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>    Affects Versions: 2.3.0
>            Reporter: Michał
>            Assignee: Michał
>            Priority: Major
>              Labels: needs-kip
>
> h2. Problem 
> The default creation of TimeWindows, like
> {code}
> TimeWindows.of(ofMillis(xxx))
> {code}
> calls an internal constructor
> {code}
> return new TimeWindows(sizeMs, sizeMs, -1, DEFAULT_RETENTION_MS);
> {code}
> And the *-1* parameter is the default grace period which I think is here for backward compatibility
> {code}
> @SuppressWarnings("deprecation") // continuing to support Windows#maintainMs/segmentInterval in fallback mode
> @Override
> public long gracePeriodMs() {
>     // NOTE: in the future, when we remove maintainMs,
>     // we should default the grace period to 24h to maintain the default behavior,
>     // or we can default to (24h - size) if you want to be super accurate.
>     return graceMs != -1 ? graceMs : maintainMs() - size();
> }
> {code}
> The problem is that if you use a TimeWindows with gracePeriod of *-1* together with suppress *untilWindowCloses*, it never emits an event.
> You can check the Suppress tests (SuppressScenarioTest.shouldSupportFinalResultsForTimeWindows), where [~vvcephei] was (maybe) aware of that and all the scenarios specify the gracePeriod.
> I will add a test without it on my branch and it will fail.
> The test: https://github.com/atais/kafka/commit/221a04dc40d636ffe93a0ad95dfc6bcad653f4db 
> h2. Now what can be done
> One easy fix would be to change the default value to 0, which works fine for me in my project, however, I am not aware of the impact it would have done due to the changes in the *gracePeriodMs* method mentioned before.



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