Github user suyanNone commented on a diff in the pull request:
https://github.com/apache/spark/pull/3574#discussion_r21359660
--- Diff: core/src/main/scala/org/apache/spark/storage/BlockManager.scala
---
@@ -1089,15 +1089,17 @@ private[spark] class BlockManager(
val info = blockInfo.get(blockId).orNull
if (info != null) {
info.synchronized {
- // Removals are idempotent in disk store and memory store. At
worst, we get a warning.
- val removedFromMemory = memoryStore.remove(blockId)
- val removedFromDisk = diskStore.remove(blockId)
- val removedFromTachyon = if (tachyonInitialized)
tachyonStore.remove(blockId) else false
- if (!removedFromMemory && !removedFromDisk && !removedFromTachyon)
{
- logWarning(s"Block $blockId could not be removed as it was not
found in either " +
- "the disk, memory, or tachyon store")
+ if (blockInfo.get(blockId).isEmpty) {
--- End diff --
1. ThreadA into RemoveBlock(), and got info for blockId1
2. ThreadB into DropFromMemory(), and got info for blockId1
now Thread A, B all want got info.sychronized
B got, and drop block(blockId) from memory, and this block is use memory
only, so it remove from blockinfo. and then release the lock.
then A got, but info is already not in blockinfo.
Did I have miss sth or misunderstand sth? may dropForMemory and removeBlock
can't happen at the same time?
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