[jira] [Updated] (FLINK-16929) Session Window produces sessions randomly

["Ori Popowski (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-16929?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ori Popowski updated FLINK-16929:
---------------------------------
    Attachment: image-2020-04-01-19-48-35-977.png

> Session Window produces sessions randomly
> -----------------------------------------
>
>                 Key: FLINK-16929
>                 URL: https://issues.apache.org/jira/browse/FLINK-16929
>             Project: Flink
>          Issue Type: Bug
>    Affects Versions: 1.9.1
>            Reporter: Ori Popowski
>            Priority: Major
>         Attachments: image-2020-04-01-19-43-07-288.png, image-2020-04-01-19-44-35-714.png, image-2020-04-01-19-48-35-977.png
>
>
> We have a Flink job which keyBys session ID (sId), and uses a session window with 30 minutes gap:
> {code:java}
> inputStream
>     .keyBy(keySelector)
>     .window(EventTimeSessionWindows.withGap(Time.minutes(30)))
>     .allowedLateness(Time.seconds(0L))
> {code}
> This Flink job reads from Kinesis stream.
> Lately (I suspect after upgrading from 1.5.4 to 1.9.1) we get too many sessions, with gaps of several seconds (instead of 30 minutes).
> We have no idea why it's happening and suspect a Flink bug or a state backend bug (we use RocksDB).
> I haven't found any indication in the logs except for some read throughput warnings which were resolved by a backoff.
> Attached is a table of derived sessions, and then the raw events
> *Sessions*
> !image-2020-04-01-19-43-07-288.png!
>  
> *Events*
> *!image-2020-04-01-19-44-35-714.png!*
>  



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