Github user kayousterhout commented on a diff in the pull request:
https://github.com/apache/spark/pull/6423#discussion_r32071240
--- Diff:
core/src/main/scala/org/apache/spark/shuffle/hash/HashShuffleReader.scala ---
@@ -33,17 +34,54 @@ private[spark] class HashShuffleReader[K, C](
"Hash shuffle currently only supports fetching one partition")
private val dep = handle.dependency
+ private val blockManager = SparkEnv.get.blockManager
/** Read the combined key-values for this reduce task */
override def read(): Iterator[Product2[K, C]] = {
+ val blockStreams = BlockStoreShuffleFetcher.fetchBlockStreams(
+ handle.shuffleId, startPartition, context)
+
+ // Wrap the streams for compression based on configuration
+ val wrappedStreams = blockStreams.map { case (blockId, inputStream) =>
+ blockManager.wrapForCompression(blockId, inputStream)
+ }
+
val ser = Serializer.getSerializer(dep.serializer)
- val iter = BlockStoreShuffleFetcher.fetch(handle.shuffleId,
startPartition, context, ser)
+ val serializerInstance = ser.newInstance()
+
+ // Create a key/value iterator for each stream
+ val recordIterator = wrappedStreams.flatMap { wrappedStream =>
+ val kvIter =
serializerInstance.deserializeStream(wrappedStream).asKeyValueIterator
+ CompletionIterator[(Any, Any), Iterator[(Any, Any)]](kvIter, {
+ // Close the stream once all the records have been read from it to
free underlying
+ // ManagedBuffer as soon as possible. Note that in case of task
failure, the task's
+ // TaskCompletionListener will make sure this is released.
+ wrappedStream.close()
+ })
+ }
+
+ // Update read metrics for each record materialized
+ val iter = new InterruptibleIterator[(Any, Any)](context,
recordIterator) {
+ val readMetrics =
context.taskMetrics.createShuffleReadMetricsForDependency()
--- End diff --
super nit: I think one space is missing here and below (this whole block
should be indented 2 spaces, and it looks like it's only indented one)
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