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Sean Owen commented on SPARK-19208: ----------------------------------- You have 29,890,095 features. At extremes of scale this might make a difference, but, this isn't at all a normal use case. The difference between 3 and 8 8-byte values per feature is, at any normal scale, trivial. I am not sure it's worth duplicating this code to optimize this. You can just write your own custom scaling for this extreme case, and, make it even more efficient. > MaxAbsScaler and MinMaxScaler are very inefficient > -------------------------------------------------- > > Key: SPARK-19208 > URL: https://issues.apache.org/jira/browse/SPARK-19208 > Project: Spark > Issue Type: Improvement > Components: ML > Reporter: zhengruifeng > Assignee: Apache Spark > Attachments: WechatIMG2621.jpeg > > > Now, {{MaxAbsScaler}} and {{MinMaxScaler}} are using > {{MultivariateOnlineSummarizer}} to compute the min/max. > However {{MultivariateOnlineSummarizer}} will also compute extra unused > statistics. It slows down the task, moreover it is more prone to cause OOM. > For example: > env : --driver-memory 4G --executor-memory 1G --num-executors 4 > data: > [http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/binary.html#kdd2010%20(bridge%20to%20algebra)] > 748401 instances, and 29,890,095 features > {{MaxAbsScaler.fit}} fails because of OOM > {{MultivariateOnlineSummarizer}} maintains 8 arrays: > {code} > private var currMean: Array[Double] = _ > private var currM2n: Array[Double] = _ > private var currM2: Array[Double] = _ > private var currL1: Array[Double] = _ > private var totalCnt: Long = 0 > private var totalWeightSum: Double = 0.0 > private var weightSquareSum: Double = 0.0 > private var weightSum: Array[Double] = _ > private var nnz: Array[Long] = _ > private var currMax: Array[Double] = _ > private var currMin: Array[Double] = _ > {code} > For {{MaxAbsScaler}}, only 1 array is needed (max of abs value) > For {{MinMaxScaler}}, only 3 arrays are needed (max, min, nnz) > After modication in the pr, the above example run successfully. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org