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https://issues.apache.org/jira/browse/SPARK-27635?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dongjoon Hyun closed SPARK-27635.
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> Prevent from splitting too many partitions smaller than row group size in
> Parquet file format
> ---------------------------------------------------------------------------------------------
>
> Key: SPARK-27635
> URL: https://issues.apache.org/jira/browse/SPARK-27635
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.4.2, 3.0.0
> Reporter: Lantao Jin
> Priority: Major
> Attachments: Screen Shot 2019-05-05 at 5.45.15 PM.png
>
>
> The scenario is submitting multiple jobs concurrently with spark dynamic
> allocation enabled. The issue happens in determining RDD partition numbers.
> When there are more available CPU cores, spark will try to split RDD to more
> pieces. But since the file is stored as parquet format, parquet's row group
> is actually the basic unit block to read data. Splitting RDD to too many
> small pieces doesn't make sense.
> Jobs will launch too many partitions and never complete.
> !Screen Shot 2019-05-05 at 5.45.15 PM.png!
> Set the default parallelism to a fixed number (for example 200) could
> workaround.
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