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From pwendell <>
Subject [GitHub] spark pull request: SPARK-1145: Memory mapping with many small blo...
Date Mon, 03 Mar 2014 20:24:08 GMT
Github user pwendell commented on a diff in the pull request:
    --- Diff: core/src/main/scala/org/apache/spark/storage/BlockFetcherIterator.scala ---
    @@ -146,6 +146,12 @@ object BlockFetcherIterator {
         protected def splitLocalRemoteBlocks(): ArrayBuffer[FetchRequest] = {
    +      // Make remote requests at most maxBytesInFlight / 5 in length; the reason to keep
    +      // smaller than maxBytesInFlight is to allow multiple, parallel fetches from up
to 5
    +      // nodes, rather than blocking on reading output from one node.
    +      val maxRequestSize = math.max(maxBytesInFlight / 5, 1L)
    --- End diff --
    if you look at the code, this is used as a threshold where if the size gets larger than
this it truncates the current request and creates a new one. I think the name was just wrong.
Also even with my change it's *sort of* wrong because in fact the request size may be slightly
larger than this.

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