[jira] [Commented] (SPARK-7122) KafkaUtils.createDirectStream - unreasonable processing time in absence of load

["Cody Koeninger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-7122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14511092#comment-14511092 ] 

Cody Koeninger commented on SPARK-7122:
---------------------------------------

Does this actually have anything to do with direct stream?  I.e. is the behavior the same with the receiver based stream?

> KafkaUtils.createDirectStream - unreasonable processing time in absence of load
> -------------------------------------------------------------------------------
>
>                 Key: SPARK-7122
>                 URL: https://issues.apache.org/jira/browse/SPARK-7122
>             Project: Spark
>          Issue Type: Question
>          Components: Streaming
>    Affects Versions: 1.3.1
>         Environment: Spark Streaming 1.3.1, standalone mode running on just 1 box: Ubuntu 14.04.2 LTS, 4 cores, 8GB RAM, java version "1.8.0_40"
>            Reporter: Platon Potapov
>            Priority: Minor
>         Attachments: 10.second.window.fast.job.txt, 5.second.window.slow.job.txt, SparkStreamingJob.scala
>
>
> attached is the complete source code of a test spark job. no external data generators are run - just the presence of a kafka topic named "raw" suffices.
> the spark job is run with no load whatsoever. http://localhost:4040/streaming is checked to obtain job processing duration.
> * in case the test contains the following transformation:
> {code}
>     // dummy transformation
>     val temperature = bytes.filter(_._1 == "abc")
>     val abc = temperature.window(Seconds(40), Seconds(5))
>     abc.print()
> {code}
> the median processing time is 3 seconds 80 ms
> * in case the test contains the following transformation:
> {code}
>     // dummy transformation
>     val temperature = bytes.filter(_._1 == "abc")
>     val abc = temperature.map(x => (1, x))
>     abc.print()
> {code}
> the median processing time is just 50 ms
> please explain why does the "window" transformation introduce such a growth of job duration?
> note: the result is the same regardless of the number of kafka topic partitions (I've tried 1 and 8)
> note2: the result is the same regardless of the window parameters (I've tried (20, 2) and (40, 5))



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