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https://issues.apache.org/jira/browse/SPARK-7122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14569125#comment-14569125
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Cody Koeninger commented on SPARK-7122:
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That number of tasks sounds normal for that many partitions, since the
direct stream partitions are 1:1 with kafka partitions.
Task overhead might explain a little bit of the difference, but I doubt
it's 6 seconds worth.
I'm not sure there's much else I can say without being able to compare the
code for the two.
On Tue, Jun 2, 2015 at 4:46 AM, Nicolas PHUNG (JIRA) <[email protected]>
> 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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