Microsoft.ML.Trainers.FastTree.IParallelTraining.FindGlobalBestSplit(Microsoft.ML.Trainers.FastTree.LeastSquaresRegressionTreeLearner.LeafSplitCandidates, Microsoft.ML.Trainers.FastTree.LeastSquaresRegressionTreeLearner.LeafSplitCandidates, Microsoft.ML.Trainers.FastTree.FindBestThresholdFromRawArrayFun, Microsoft.ML.Trainers.FastTree.LeastSquaresRegressionTreeLearner.SplitInfo[])