Github user liancheng commented on a diff in the pull request:

    https://github.com/apache/spark/pull/96#discussion_r10388071
  
    --- 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 --
    
    No, @mridulm `entries` is constructed with `accessOrder` set to be `true`, 
which enables LRU. Thanks for pointing this out @mridulm, wasn't aware of that 
before.


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