[jira] [Commented] (SPARK-25283) A deadlock in UnionRDD

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-25283?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16597391#comment-16597391 ] 

Apache Spark commented on SPARK-25283:
--------------------------------------

User 'MaxGekk' has created a pull request for this issue:
https://github.com/apache/spark/pull/22283

> A deadlock in UnionRDD
> ----------------------
>
>                 Key: SPARK-25283
>                 URL: https://issues.apache.org/jira/browse/SPARK-25283
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 2.4.0
>            Reporter: Maxim Gekk
>            Priority: Major
>
> The PR https://github.com/apache/spark/pull/21913 replaced Scala parallel collections in UnionRDD by new parmap function. This changes cause a deadlock in the partitions method. The code demonstrates the problem:
> {code:scala}
>     val wide = 20
>     def unionRDD(num: Int): UnionRDD[Int] = {
>       val rdds = (0 until num).map(_ => sc.parallelize(1 to 10, 1))
>       new UnionRDD(sc, rdds)
>     }
>     val level0 = (0 until wide).map { _ =>
>       val level1 = (0 until wide).map(_ => unionRDD(wide))
>       new UnionRDD(sc, level1)
>     }
>     val rdd = new UnionRDD(sc, level0)
>     rdd.partitions.length
> {code}



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