Github user rxin commented on a diff in the pull request:
https://github.com/apache/spark/pull/12352#discussion_r60171658
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileScanRDD.scala
---
@@ -53,33 +55,74 @@ class FileScanRDD(
override def compute(split: Partition, context: TaskContext):
Iterator[InternalRow] = {
val iterator = new Iterator[Object] with AutoCloseable {
+ private val inputMetrics = context.taskMetrics().inputMetrics
+ private val existingBytesRead = inputMetrics.bytesRead
+
+ // Find a function that will return the FileSystem bytes read by
this thread. Do this before
+ // apply readFunction, because it might read some bytes.
+ private val getBytesReadCallback: Option[() => Long] =
+ SparkHadoopUtil.get.getFSBytesReadOnThreadCallback()
+
+ // For Hadoop 2.5+, we get our input bytes from thread-local Hadoop
FileSystem statistics.
+ // If we do a coalesce, however, we are likely to compute multiple
partitions in the same
+ // task and in the same thread, in which case we need to avoid
override values written by
+ // previous partitions (SPARK-13071).
+ private def updateBytesRead(): Unit = {
+ getBytesReadCallback.foreach { getBytesRead =>
+ inputMetrics.setBytesRead(existingBytesRead + getBytesRead())
+ }
+ }
+
+ // If we can't get the bytes read from the FS stats, fall back to
the file size,
+ // which may be inaccurate.
+ private def updateBytesReadWithFileSize(): Unit = {
+ if (getBytesReadCallback.isEmpty && currentFile != null) {
+ inputMetrics.incBytesRead(currentFile.length)
+ }
+ }
+
private[this] val files =
split.asInstanceOf[FilePartition].files.toIterator
+ private[this] var currentFile: PartitionedFile = null
private[this] var currentIterator: Iterator[Object] = null
def hasNext = (currentIterator != null && currentIterator.hasNext)
|| nextIterator()
- def next() = currentIterator.next()
+ def next() = {
+ val nextElement = currentIterator.next()
+ nextElement match {
--- End diff --
i don't know what the performance impact is to have pattern matching here.
can you just change this to an if/else and do the isInstanceOf check?
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