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Posted to issues@spark.apache.org by "Hyukjin Kwon (JIRA)" <ji...@apache.org> on 2019/05/21 03:59:13 UTC
[jira] [Updated] (SPARK-22411) Heuristic to combine splits in
DataSourceScanExec isn't accurate when dynamic allocation is enabled
[ https://issues.apache.org/jira/browse/SPARK-22411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hyukjin Kwon updated SPARK-22411:
---------------------------------
Labels: bulk-closed (was: )
> Heuristic to combine splits in DataSourceScanExec isn't accurate when dynamic allocation is enabled
> ---------------------------------------------------------------------------------------------------
>
> Key: SPARK-22411
> URL: https://issues.apache.org/jira/browse/SPARK-22411
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Vinitha Reddy Gankidi
> Assignee: Vinitha Reddy Gankidi
> Priority: Major
> Labels: bulk-closed
>
> The heuristic to calculate the maxSplitSize in DataSourceScanExec is as follows:
> https://github.com/apache/spark/blob/d28d5732ae205771f1f443b15b10e64dcffb5ff0/sql/core/src/main/scala/org/apache/spark/sql/execution/DataSourceScanExec.scala#L431
> bytesPerCore is calculated based on the default parallelism. Default parallelism in this case is the number of total cores of all the registered executors for this application. The heuristic works well with static allocation but with dynamic allocation enabled, defaultParallelism is usually one (with default config of min and initial executors as zero) at the time of split calculation. This heuristic was introduced in SPARK-14582.
> With Dynamic allocation it is confusing to tune the split size with this heuristic. It is better to ignore bytesPerCore and use the values of 'spark.sql.files.maxPartitionBytes' as the max split size.
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