Github user mridulm commented on a diff in the pull request:
https://github.com/apache/spark/pull/96#discussion_r10386811
--- Diff: core/src/main/scala/org/apache/spark/storage/MemoryStore.scala ---
@@ -236,13 +236,23 @@ private class MemoryStore(blockManager: BlockManager,
maxMemory: Long)
while (maxMemory - (currentMemory - selectedMemory) < space &&
iterator.hasNext) {
val pair = iterator.next()
val blockId = pair.getKey
- if (rddToAdd.isDefined && rddToAdd == getRddId(blockId)) {
- logInfo("Will not store " + blockIdToAdd + " as it would
require dropping another " +
- "block from the same RDD")
- return false
+ // Apply the same-RDD rule for cache replacement. Quoted from the
+ // original RDD paper:
+ //
+ // When a new RDD partition is computed but there is not
enough
+ // space to store it, we evict a partition from the least
recently
+ // accessed RDD, unless this is the same RDD as the one with
the
+ // new partition. In that case, we keep the old partition in
memory
+ // to prevent cycling partitions from the same RDD in and out.
+ //
+ // TODO implement LRU eviction
--- End diff --
entries is already a LinkedHashMap - so you iterate in LRU : you can remove
the comment.
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