Github user steveloughran commented on a diff in the pull request:
https://github.com/apache/spark/pull/13830#discussion_r72242750
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ListingFileCatalog.scala
---
@@ -73,21 +73,67 @@ class ListingFileCatalog(
cachedPartitionSpec = null
}
- protected def listLeafFiles(paths: Seq[Path]):
mutable.LinkedHashSet[FileStatus] = {
+ /**
+ * List leaf files of given paths. This method will submit a Spark job
to do parallel
+ * listing whenever there is a path having more files than the parallel
partition discovery
+ * discovery threshold.
+ */
+ protected[spark] def listLeafFiles(paths: Seq[Path]):
mutable.LinkedHashSet[FileStatus] = {
if (paths.length >=
sparkSession.sessionState.conf.parallelPartitionDiscoveryThreshold) {
HadoopFsRelation.listLeafFilesInParallel(paths, hadoopConf,
sparkSession)
} else {
+ // Right now, the number of paths is less than the value of
+ // parallelPartitionDiscoveryThreshold. So, we will list file
statues at the driver.
+ // If there is any child that has more files than the threshold, we
will use parallel
+ // listing.
+
// Dummy jobconf to get to the pathFilter defined in configuration
val jobConf = new JobConf(hadoopConf, this.getClass)
val pathFilter = FileInputFormat.getInputPathFilter(jobConf)
+
val statuses: Seq[FileStatus] = paths.flatMap { path =>
val fs = path.getFileSystem(hadoopConf)
logTrace(s"Listing $path on driver")
- Try {
- HadoopFsRelation.listLeafFiles(fs, fs.getFileStatus(path),
pathFilter)
- }.getOrElse(Array.empty[FileStatus])
+
+ val childStatuses = {
+ // TODO: We need to avoid of using Try at here.
+ val stats =
Try(fs.listStatus(path)).getOrElse(Array.empty[FileStatus])
+ if (pathFilter != null) stats.filter(f =>
pathFilter.accept(f.getPath)) else stats
+ }
+
+ childStatuses.map {
+ case f: LocatedFileStatus => f
+
+ // NOTE:
+ //
+ // - Although S3/S3A/S3N file system can be quite slow for
remote file metadata
+ // operations, calling `getFileBlockLocations` does no harm
here since these file system
+ // implementations don't actually issue RPC for this method.
+ //
--- End diff --
while you are correct about s3a, the openstack swift client does do RPC
here, as swift instances can exhibit locality, as does Azure. This comment
isn't actually correct.
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