Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/11534#discussion_r55279952
--- Diff: core/src/main/scala/org/apache/spark/storage/BlockManager.scala
---
@@ -422,108 +462,52 @@ private[spark] class BlockManager(
Option(
shuffleBlockResolver.getBlockData(blockId.asInstanceOf[ShuffleBlockId]).nioByteBuffer())
} else {
- doGetLocal(blockId, asBlockResult =
false).asInstanceOf[Option[ByteBuffer]]
+ blockInfoManager.lockForReading(blockId) match {
+ case None =>
+ logDebug(s"Block $blockId was not found")
+ None
+ case Some(info) =>
+ Some(doGetLocalBytes(blockId, info))
+ }
}
}
- private def doGetLocal(blockId: BlockId, asBlockResult: Boolean):
Option[Any] = {
- blockInfoManager.lockForReading(blockId) match {
- case None =>
- logDebug(s"Block $blockId was not found")
- None
- case Some(info) =>
- val level = info.level
- logDebug(s"Level for block $blockId is $level")
-
- // Look for the block in memory
+ private def doGetLocalBytes(blockId: BlockId, info: BlockInfo):
ByteBuffer = {
+ val level = info.level
+ logDebug(s"Level for block $blockId is $level")
+ if (level.deserialized) {
--- End diff --
`level-deserialized` specifies that this block's in-memory values will be
stored as Java objects. For a block at this storage level, there are three
possibilities:
1. it's stored as java objects in memory
2. it's stored as bytes on disk
3. an error has occurred and the block is missing
The logic inside of this `if` case tries to check case 2 ahead of case 1 so
that we avoid unnecessary serialization if a serialized copy already exists on
disk.
Were you confused about the fact that we can call `getLocalBytes()` on a
block which is cached as java objects?
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