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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2019/03/06 09:15:00 UTC

[jira] [Assigned] (SPARK-27070) DefaultPartitionCoalescer can lock up driver for hours

     [ https://issues.apache.org/jira/browse/SPARK-27070?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-27070:
------------------------------------

    Assignee:     (was: Apache Spark)

> DefaultPartitionCoalescer can lock up driver for hours
> ------------------------------------------------------
>
>                 Key: SPARK-27070
>                 URL: https://issues.apache.org/jira/browse/SPARK-27070
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 2.3.1, 2.3.2, 2.4.0
>            Reporter: Yuli Fiterman
>            Priority: Major
>
> We're running Spark on EMR reading large datasets from S3. When trying to coalesce a UnionRDD of two large FileScanRDDs (each with a few million partitions) into around 8k partitions the driver can stall for over an hour. 
>  
> Profiler shows that over 90% of the time is spent in TimSort which is invoked by `pickBin`. This seems like a very inefficient way to find the least occupied PartitionGroup. IMO a better way would just using the `min` method on the ArrayBuffer of `PartitionGroup`s



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