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From Fabian Hueske <fhue...@gmail.com>
Subject Re: When does Trigger.clear() get called?
Date Fri, 12 Oct 2018 07:48:11 GMT
Hi Andrew,

The PURGE action of a window removes the window state (i.e., the collected
events or computed aggregate) but the window meta data including the
Trigger remain.
The Trigger.close() method is called, when the winodw is completely (i.e.,
all meta data) discarded. This happens, when the time (wallclock time for
processing time or watermark for event time windows) exceeds the window's
end timestamp.

Best, Fabian

Am Fr., 12. Okt. 2018 um 05:25 Uhr schrieb Hequn Cheng <chenghequn@gmail.com

> Hi Andrew,
> Do you use CountWindow? You can switch to TimeWindow to have a test.
> I'm not quite familiar with window. I checked the code and found that
> clear() is called only when timer is triggered, i.e, called at the end of
> time window.
> Hope this helps.
> Best, Hequn
> On Fri, Oct 12, 2018 at 6:23 AM Andrew Danks <a.danks@gmail.com> wrote:
>> Hello,
>> I see that the clear() function is implemented for various types of
>> Triggers in the Flink API. For example:
>> https://github.com/apache/flink/blob/release-1.3/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/triggers/ContinuousProcessingTimeTrigger.java#L87
>> I am working on a custom Trigger for my application and have implemented
>> clear() in a similar way.
>> However, having put a breakpoint in this function it doesn’t seem to get
>> called when I expect. The source code says that is called "when a window is
>> purged”[1] but when my Trigger emits a PURGE this function never seems to
>> get called. I am on Flink 1.3.
>> Hoping someone can shed more light on the purpose of clear() and how/when
>> it gets called
>> Thanks!
>> Andrew
>> [1]
>> https://github.com/apache/flink/blob/release-1.3/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/triggers/Trigger.java#L111

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