Github user pwendell commented on a diff in the pull request:
https://github.com/apache/spark/pull/242#discussion_r11380471
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/recommendation/ALS.scala ---
@@ -421,12 +421,12 @@ class ALS private (
* Compute the new feature vectors for a block of the users matrix given
the list of factors
* it received from each product and its InLinkBlock.
*/
- private def updateBlock(messages: Seq[(Int, Array[Array[Double]])],
inLinkBlock: InLinkBlock,
+ private def updateBlock(messages: Iterable[(Int, Array[Array[Double]])],
inLinkBlock: InLinkBlock,
rank: Int, lambda: Double, alpha: Double, YtY:
Option[Broadcast[DoubleMatrix]])
: Array[Array[Double]] =
{
// Sort the incoming block factor messages by block ID and make them
an array
- val blockFactors = messages.sortBy(_._1).map(_._2).toArray //
Array[Array[Double]]
+ val blockFactors = messages.toArray.sortBy(_._1).map(_._2) //
Array[Array[Double]]
--- End diff --
@mateiz is this an expensive thing here? this will make an extra copy of
this sequence.
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