feat: added chunk size parameter for copying java data to native

src/main/scala/com/microsoft/ml/spark/lightgbm/LightGBMClassifier.scala

@@ -49,7 +49,8 @@ class LightGBMClassifier(override val uid: String)
       getFeatureFraction, getMaxDepth, getMinSumHessianInLeaf, numTasks, getObjective, modelStr,
       getIsUnbalance, getVerbosity, categoricalIndexes, actualNumClasses, getBoostFromAverage,
       getBoostingType, getLambdaL1, getLambdaL2, getIsProvideTrainingMetric,
-      getMetric, getMinGainToSplit, getMaxDeltaStep, getMaxBinByFeature, getMinDataInLeaf, getSlotNames, getDelegate)
+      getMetric, getMinGainToSplit, getMaxDeltaStep, getMaxBinByFeature, getMinDataInLeaf, getSlotNames,
+      getDelegate, getChunkSize)
   }
 
   def getModel(trainParams: TrainParams, lightGBMBooster: LightGBMBooster): LightGBMClassificationModel = {

src/main/scala/com/microsoft/ml/spark/lightgbm/LightGBMParams.scala

@@ -77,6 +77,15 @@ trait LightGBMExecutionParams extends Wrappable {
 
   def getNumTasks: Int = $(numTasks)
   def setNumTasks(value: Int): this.type = set(numTasks, value)
+
+  val chunkSize = new IntParam(this, "chunkSize",
+    "Advanced parameter to specify the chunk size for copying Java data to native.  " +
+      "If set too high, memory may be wasted, but if set too low, performance may be reduced during data copy." +
+      "If dataset size is known beforehand, set to the number of rows in the dataset.")
+  setDefault(chunkSize -> 10000)
+
+  def getChunkSize: Int = $(chunkSize)
+  def setChunkSize(value: Int): this.type = set(chunkSize, value)
 }
 
 /** Defines common parameters across all LightGBM learners related to learning score evolution.

src/main/scala/com/microsoft/ml/spark/lightgbm/LightGBMRanker.scala

@@ -56,7 +56,7 @@ class LightGBMRanker(override val uid: String)
       getFeatureFraction, getMaxDepth, getMinSumHessianInLeaf, numTasks, modelStr,
       getVerbosity, categoricalIndexes, getBoostingType, getLambdaL1, getLambdaL2, getMaxPosition, getLabelGain,
       getIsProvideTrainingMetric, getMetric, getEvalAt, getMinGainToSplit, getMaxDeltaStep,
-      getMaxBinByFeature, getMinDataInLeaf, getSlotNames, getDelegate)
+      getMaxBinByFeature, getMinDataInLeaf, getSlotNames, getDelegate, getChunkSize)
   }
 
   def getModel(trainParams: TrainParams, lightGBMBooster: LightGBMBooster): LightGBMRankerModel = {

src/main/scala/com/microsoft/ml/spark/lightgbm/LightGBMRegressor.scala

@@ -63,7 +63,7 @@ class LightGBMRegressor(override val uid: String)
       getEarlyStoppingRound, getImprovementTolerance, getFeatureFraction, getMaxDepth, getMinSumHessianInLeaf,
       numTasks, modelStr, getVerbosity, categoricalIndexes, getBoostFromAverage, getBoostingType, getLambdaL1,
       getLambdaL2, getIsProvideTrainingMetric, getMetric, getMinGainToSplit, getMaxDeltaStep,
-      getMaxBinByFeature, getMinDataInLeaf, getSlotNames, getDelegate)
+      getMaxBinByFeature, getMinDataInLeaf, getSlotNames, getDelegate, getChunkSize)
   }
 
   def getModel(trainParams: TrainParams, lightGBMBooster: LightGBMBooster): LightGBMRegressionModel = {

src/main/scala/com/microsoft/ml/spark/lightgbm/LightGBMUtils.scala

@@ -209,9 +209,9 @@ object LightGBMUtils {
     (lightgbmlib.double_to_voidp_ptr(data), data)
   }
 
-  def getNumRowsForChunksArray(numRows: Int, numCols: Int, defaultChunkSize: Int): SWIGTYPE_p_int = {
-    var numChunks = Math.floorDiv(numRows, defaultChunkSize)
-    var leftoverChunk = numRows % defaultChunkSize
+  def getNumRowsForChunksArray(numRows: Int, chunkSize: Int): SWIGTYPE_p_int = {
+    var numChunks = Math.floorDiv(numRows, chunkSize)
+    var leftoverChunk = numRows % chunkSize
     if (leftoverChunk > 0) {
       numChunks += 1
     }
@@ -220,7 +220,7 @@ object LightGBMUtils {
       if (index == numChunks - 1 && leftoverChunk > 0) {
         lightgbmlib.intArray_setitem(numRowsForChunks, index, leftoverChunk)
       } else {
-        lightgbmlib.intArray_setitem(numRowsForChunks, index, defaultChunkSize)
+        lightgbmlib.intArray_setitem(numRowsForChunks, index, chunkSize)
       }
     })
     numRowsForChunks
@@ -229,7 +229,7 @@ object LightGBMUtils {
   def generateDenseDataset(numRows: Int, numCols: Int, featuresArray: doubleChunkedArray,
                            referenceDataset: Option[LightGBMDataset],
                            featureNamesOpt: Option[Array[String]],
-                           trainParams: TrainParams, defaultChunkSize: Int): LightGBMDataset = {
+                           trainParams: TrainParams, chunkSize: Int): LightGBMDataset = {
     val isRowMajor = 1
     val datasetOutPtr = lightgbmlib.voidpp_handle()
     val datasetParams = s"max_bin=${trainParams.maxBin} is_pre_partition=True " +
@@ -238,7 +238,7 @@ object LightGBMUtils {
       else s"categorical_feature=${trainParams.categoricalFeatures.mkString(",")}")
     val data64bitType = lightgbmlibConstants.C_API_DTYPE_FLOAT64
     var data: Option[(SWIGTYPE_p_void, SWIGTYPE_p_double)] = None
-    val numRowsForChunks = getNumRowsForChunksArray(numRows, numCols, defaultChunkSize)
+    val numRowsForChunks = getNumRowsForChunksArray(numRows, chunkSize)
     try {
       // Generate the dataset for features
       featuresArray.get_last_chunk_add_count()
@@ -249,6 +249,7 @@ object LightGBMUtils {
         "Dataset create")
     } finally {
       featuresArray.release()
+      lightgbmlib.delete_intArray(numRowsForChunks)
     }
     val dataset = new LightGBMDataset(lightgbmlib.voidpp_value(datasetOutPtr))
     dataset.setFeatureNames(featureNamesOpt, numCols)

src/main/scala/com/microsoft/ml/spark/lightgbm/TrainParams.scala

@@ -39,6 +39,7 @@ abstract class TrainParams extends Serializable {
   def minDataInLeaf: Int
   def featureNames: Array[String]
   def delegate: Option[LightGBMDelegate]
+  def chunkSize: Int
 
   override def toString: String = {
     // Since passing `isProvideTrainingMetric` to LightGBM as a config parameter won't work,
@@ -71,7 +72,8 @@ case class ClassifierTrainParams(parallelism: String, topK: Int, numIterations:
                                  boostingType: String, lambdaL1: Double, lambdaL2: Double,
                                  isProvideTrainingMetric: Boolean, metric: String, minGainToSplit: Double,
                                  maxDeltaStep: Double, maxBinByFeature: Array[Int], minDataInLeaf: Int,
-                                 featureNames: Array[String], delegate: Option[LightGBMDelegate])
+                                 featureNames: Array[String], delegate: Option[LightGBMDelegate],
+                                 chunkSize: Int)
   extends TrainParams {
   override def toString(): String = {
     val extraStr =
@@ -95,7 +97,8 @@ case class RegressorTrainParams(parallelism: String, topK: Int, numIterations: I
                                 boostingType: String, lambdaL1: Double, lambdaL2: Double,
                                 isProvideTrainingMetric: Boolean, metric: String, minGainToSplit: Double,
                                 maxDeltaStep: Double, maxBinByFeature: Array[Int], minDataInLeaf: Int,
-                                featureNames: Array[String], delegate: Option[LightGBMDelegate])
+                                featureNames: Array[String], delegate: Option[LightGBMDelegate],
+                                chunkSize: Int)
   extends TrainParams {
   override def toString(): String = {
     s"alpha=$alpha tweedie_variance_power=$tweedieVariancePower boost_from_average=${boostFromAverage.toString} " +
@@ -116,7 +119,8 @@ case class RankerTrainParams(parallelism: String, topK: Int, numIterations: Int,
                              labelGain: Array[Double], isProvideTrainingMetric: Boolean,
                              metric: String, evalAt: Array[Int], minGainToSplit: Double,
                              maxDeltaStep: Double, maxBinByFeature: Array[Int], minDataInLeaf: Int,
-                             featureNames: Array[String], delegate: Option[LightGBMDelegate])
+                             featureNames: Array[String], delegate: Option[LightGBMDelegate],
+                             chunkSize: Int)
   extends TrainParams {
   override def toString(): String = {
     val labelGainStr =

src/main/scala/com/microsoft/ml/spark/lightgbm/TrainUtils.scala

@@ -112,10 +112,10 @@ private object TrainUtils extends Serializable {
                                  referenceDataset: Option[LightGBMDataset], schema: StructType,
                                  log: Logger, trainParams: TrainParams): Option[LightGBMDataset] = {
     var numRows = 0
-    val defaultChunkSize = 1000
-    val labelsChunkedArray = new floatChunkedArray(defaultChunkSize)
-    val weightChunkedArrayOpt = columnParams.weightColumn.map { _ => new floatChunkedArray(defaultChunkSize) }
-    val initScoreChunkedArrayOpt = columnParams.initScoreColumn.map { _ => new doubleChunkedArray(defaultChunkSize) }
+    val chunkSize = trainParams.chunkSize
+    val labelsChunkedArray = new floatChunkedArray(chunkSize)
+    val weightChunkedArrayOpt = columnParams.weightColumn.map { _ => new floatChunkedArray(chunkSize) }
+    val initScoreChunkedArrayOpt = columnParams.initScoreColumn.map { _ => new doubleChunkedArray(chunkSize) }
     var featuresChunkedArrayOpt: Option[doubleChunkedArray] = None
     val groupColumnValues: ListBuffer[Row] = new ListBuffer[Row]()
     try {
@@ -130,7 +130,7 @@ private object TrainUtils extends Serializable {
         val rowAsDoubleArray = getRowAsDoubleArray(row, columnParams, schema)
         numCols = rowAsDoubleArray.length
         if (featuresChunkedArrayOpt.isEmpty) {
-          featuresChunkedArrayOpt = Some(new doubleChunkedArray(numCols * defaultChunkSize))
+          featuresChunkedArrayOpt = Some(new doubleChunkedArray(numCols * chunkSize))
         }
         addFeaturesToChunkedArray(featuresChunkedArrayOpt, numCols, rowAsDoubleArray)
         addInitScoreColumnRow(initScoreChunkedArrayOpt, row, columnParams, schema)
@@ -140,7 +140,7 @@ private object TrainUtils extends Serializable {
       val slotNames = getSlotNames(schema, columnParams.featuresColumn, numCols, trainParams)
       log.info(s"LightGBM task generating dense dataset with $numRows rows and $numCols columns")
       val datasetPtr = Some(LightGBMUtils.generateDenseDataset(numRows, numCols, featuresChunkedArrayOpt.get,
-        referenceDataset, slotNames, trainParams, defaultChunkSize))
+        referenceDataset, slotNames, trainParams, chunkSize))
       datasetPtr.get.addFloatField(labelsChunkedArray, "label", numRows)
 
       weightChunkedArrayOpt.foreach(datasetPtr.get.addFloatField(_, "weight", numRows))