Re: EventTimeSessionWindow firing too soon

Posted by Aljoscha Krettek on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/EventTimeSessionWindow-firing-too-soon-tp35959p35994.html

Hi,

what is the timescale of your data in Kafka. If you have data in there
that spans more than ~30 minutes I would expect your windows to fire
very soon after the job is started. Event time does not depend on a wall
clock but instead advances with the time in the stream. As Flink
advances through the data in Kafka so does event-time advance in step.

Does that explain your situation?

Best,
Aljoscha

On 15.06.20 16:49, Ori Popowski wrote:

> I'm using Flink 1.10 on YARN, and I have a EventTimeSessionWindow with a
> gap of 30 minutes.
>
> But as soon as I start the job, events are written to the sink (I can see
> them in S3) even though 30 minutes have not passed.
>
> This is my job:
>
> val stream = senv
>        .addSource(new FlinkKafkaConsumer("…", compressedEventDeserializer,
> properties))
>        .filter(_.sessionId.nonEmpty)
>        .flatMap(_ match { case (_, events) => events })
>        .assignTimestampsAndWatermarks(new
> TimestampExtractor[Event](Time.minutes(10)) {
>          override def extractTimestamp(element: Event): Long =
> event.sequence / 1000 // microseconds
>        })
>        .keyBy(_.sessionId)
>        .window(EventTimeSessionWindows.withGap(Time.of(30, MINUTES)))
>        .process(myProcessWindowFunction)
>
> AsyncDataStream.unorderedWait(stream, myAsyncS3Writer, 30, SECONDS, 100)
>
> Any idea why it's happening?
>