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https://issues.apache.org/jira/browse/SPARK-17842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15561099#comment-15561099
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Liwei Lin commented on SPARK-17842:
-----------------------------------

[~sreelalsl] thanks for the very clear reproducer -- it can be easily 
reproduced against 2.0 and master(as of 
8a6bbe095b6a9aa33989c0deaa5ed0128d70320f).

I'll submit a patch.

> Thread and memory leak in WindowDstream (UnionRDD ) when parallelPartition 
> computation gets enabled. 
> -----------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-17842
>                 URL: https://issues.apache.org/jira/browse/SPARK-17842
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core, Streaming
>    Affects Versions: 2.0.0
>         Environment: Yarn cluster, Eclipse Dev Env
>            Reporter: Sreelal S L
>            Priority: Critical
>
> We noticed a steady increase in ForkJoinTask instances in the driver process 
> heap. Found out the root cause to be UnionRDD.
> WindowDstream internally uses UnionRDD which has a parallel partition 
> computation logic by using parallel collection with ForkJoinPool task 
> support. 
> partitionEvalTaskSupport =new ForkJoinTaskSupport(new ForkJoinPool(8))
> The pool is created each time when a UnionRDD is created , but the pool is 
> not getting shutdown. This is leaking thread/mem every slide interval of the 
> window. 
> Easily reproducible with the below code. Just keep a watch on the number of 
> threads. 
> {code}
>     val sparkConf = new 
> SparkConf().setMaster("local[*]").setAppName("TestLeak")
>     val ssc = new StreamingContext(sparkConf, Seconds(1))
>     ssc.checkpoint("checkpoint")
>     val rdd = ssc.sparkContext.parallelize(List(1,2,3))
>     val constStream = new ConstantInputDStream[Int](ssc,rdd)
>     constStream.window(Seconds(20),Seconds(1)).print()
>     ssc.start()
>     ssc.awaitTermination();
> {code}
> This happens only when the number of rdds to be unioned is above the value 
> spark.rdd.parallelListingThreshold (By default 10)
> Currently i'm working around by setting this threshold be a higher value. 
>  



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