Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/12243#discussion_r58989411
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileScanRDD.scala
---
@@ -46,37 +50,80 @@ case class PartitionedFile(
*/
case class FilePartition(index: Int, files: Seq[PartitionedFile]) extends
Partition
+object FileScanRDD {
+ private val ioExecutionContext = ExecutionContext.fromExecutorService(
+ ThreadUtils.newDaemonCachedThreadPool("FileScanRDD", 16))
+}
+
class FileScanRDD(
@transient val sqlContext: SQLContext,
readFunction: (PartitionedFile) => Iterator[InternalRow],
@transient val filePartitions: Seq[FilePartition])
extends RDD[InternalRow](sqlContext.sparkContext, Nil) {
+ /**
+ * To get better interleaving of CPU and IO, this RDD will create a
future to prepare the next
+ * file while the current one is being processed. `currentIterator` is
the current file and
+ * `nextFile` is the future that will initialize the next file to be
read. This includes things
+ * such as starting up connections to open the file and any initial
buffering. The expectation
+ * is that `currentIterator` is CPU intensive and `nextFile` is IO
intensive.
+ */
+ val asyncIO = sqlContext.conf.filesAsyncIO
+
+ case class NextFile(file: PartitionedFile, iter: Iterator[Object])
+
override def compute(split: Partition, context: TaskContext):
Iterator[InternalRow] = {
val iterator = new Iterator[Object] with AutoCloseable {
private[this] val files =
split.asInstanceOf[FilePartition].files.toIterator
+ // TODO: do we need to close this?
--- End diff --
what does this todo mean?
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