Issue in saving Xgboost model in spark scala - scala

Question

I trained a xgboost model in spark scala as follows:
val xgbParamGrid = new ParamGridBuilder()
.addGrid(xgb.maxDepth, Array(5, 10))
.addGrid(xgb.maxBins, Array(2))
.addGrid(xgb.minChildWeight, Array(0.2))
.addGrid(xgb.eta, Array(0.015))
.addGrid(xgb.alpha, Array(0.8, 0.9))
.addGrid(xgb.lambda, Array(0.9, 1.0))
.build()
// Create the XGBoost pipeline
val pipeline = new Pipeline().setStages(Array(xgb))
val evaluator = new MulticlassClassificationEvaluator()
.setLabelCol("label")
.setPredictionCol("prediction")
.setMetricName("accuracy")
val cv = new CrossValidator()
.setEstimator(pipeline)
.setEvaluator(evaluator)
.setEstimatorParamMaps(xgbParamGrid)
.setNumFolds(3)
val xgbModel = cv.fit(trainingData)
val xgbBest = xgbModel.bestModel.asInstanceOf[PipelineModel].stages(0).asInstanceOf[XGBoostClassificationModel]
Then I tried to save it to local as:
xgbBest.write.overwrite.save(modelSavePath)
but got error message as:
Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long
at scala.runtime.BoxesRunTime.unboxToLong(BoxesRunTime.java:105)
at org.apache.spark.ml.param.LongParam.jsonEncode(params.scala:480)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$$anonfun$1$$anonfun$3.apply(DefaultXGBoostParamsWriter.scala:73)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$$anonfun$1$$anonfun$3.apply(DefaultXGBoostParamsWriter.scala:71)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
at scala.collection.AbstractTraversable.map(Traversable.scala:104)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$$anonfun$1.apply(DefaultXGBoostParamsWriter.scala:71)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$$anonfun$1.apply(DefaultXGBoostParamsWriter.scala:69)
at scala.Option.getOrElse(Option.scala:121)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$.getMetadataToSave(DefaultXGBoostParamsWriter.scala:69)
at ml.dmlc.xgboost4j.scala.spark.params.DefaultXGBoostParamsWriter$.saveMetadata(DefaultXGBoostParamsWriter.scala:51)
at ml.dmlc.xgboost4j.scala.spark.XGBoostClassificationModel$XGBoostClassificationModelWriter.saveImpl(XGBoostClassifier.scala:480)
at org.apache.spark.ml.util.MLWriter.save(ReadWrite.scala:103)
at classificationWithXgboost$.main(classificationWithXgboost.scala:125)
at classificationWithXgboost.main(classificationWithXgboost.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.spark.deploy.JavaMainApplication.start(SparkApplication.scala:52)
at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:894)
at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:198)
at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:228)
at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:137)
at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Can anyone help with the problem? Thanks