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From "Paolo Rendano (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (FLINK-7606) CEP operator leaks state
Date Thu, 05 Oct 2017 15:40:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-7606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16193026#comment-16193026
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Paolo Rendano edited comment on FLINK-7606 at 10/5/17 3:39 PM:
---------------------------------------------------------------

IMO the timeout should be triggered after the expiration of the time window (in the example
5 minutes) without any new elements (i.e. if the last received element is out of that time
window). With this kind of strategy you would get at most a latency of the time window interval.
Would it solve?


was (Author: info@paolorendano.it):
IMO the timeout should be triggered after the expiration of the time window (in the example
10 minutes) without any new elements (i.e. if the last received element is out of that time
window). With this kind of strategy you would get at most a latency of the time window interval.
Would it solve?

> CEP operator leaks state
> ------------------------
>
>                 Key: FLINK-7606
>                 URL: https://issues.apache.org/jira/browse/FLINK-7606
>             Project: Flink
>          Issue Type: Bug
>          Components: CEP
>    Affects Versions: 1.3.1
>            Reporter: Matteo Ferrario
>         Attachments: heap-dump1.png, heap-dump2.png, heap-dump3.png, Schermata 2017-09-27
alle 00.35.53.png
>
>
> The NestedMapsStateTable grows up continuously without free the heap memory.
> We created a simple job that processes a stream of messages and uses CEP to generate
an outcome message when a specific pattern is identified.
> The messages coming from the stream are grouped by a key defined in a specific field
of the message.
> We've also added the "within" clause (set as 5 minutes), indicating that two incoming
messages match the pattern only if they come in a certain time window.
> What we've seen is that for every key present in the message, an NFA object is instantiated
in the NestedMapsStateTable and it is never deallocated.
> Also the "within" clause didn't help: we've seen that if we send messages that don't
match the pattern, the memory grows up (I suppose that the state of NFA is updated) but it
is not cleaned also after the 5 minutes of time window defined in "within" clause.
> If you need, I can provide more details about the job we've implemented and also the
screenshots about the memory leak.



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