[
https://issues.apache.org/jira/browse/SPARK-21056?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16045919#comment-16045919
]
Apache Spark commented on SPARK-21056:
--------------------------------------
User 'bbossy' has created a pull request for this issue:
https://github.com/apache/spark/pull/18269
> InMemoryFileIndex.listLeafFiles should create at most one spark job when
> listing files in parallel
> --------------------------------------------------------------------------------------------------
>
> Key: SPARK-21056
> URL: https://issues.apache.org/jira/browse/SPARK-21056
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.1.1, 2.2.0
> Reporter: Bertrand Bossy
>
> Given partitioned file relation (e.g. parquet):
> {code}
> root/a=../b=../c=..
> {code}
> InMemoryFileIndex.listLeafFiles runs numberOfPartitions(a) times
> numberOfPartitions(b) spark jobs sequentially to list leaf files, if both
> numberOfPartitions(a) and numberOfPartitions(b) are below
> {{spark.sql.sources.parallelPartitionDiscovery.threshold}} and
> numberOfPartitions(c) is above
> {{spark.sql.sources.parallelPartitionDiscovery.threshold}}
> Since the jobs are run sequentially, the overhead of the jobs dominates and
> the file listing operation can become significantly slower than listing the
> files from the driver.
> I propose that InMemoryFileIndex.listLeafFiles should launch at most one
> spark job for listing leaf files.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
