[mmlspark=0.17] LightGBMRegressor failing due to Connection Exception

environment= spark 2.4 on k8s
Executor stacktrace

[2019-08-12T10:15:07.103Z] spark.org.apache.spark.executor.Executor ERROR: appId: 901C9278-B4E9-4EBB-AABF-8DB9C4DEF974, du: 1, message: Exception in task 1.0 in stage 30.0 (TID 1429) java.lang.NullPointerException at com.microsoft.ml.spark.TrainUtils$.networkInit(TrainUtils.scala:275) at com.microsoft.ml.spark.TrainUtils$.trainLightGBM(TrainUtils.scala:313) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:188) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:185) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90) at org.apache.spark.scheduler.Task.run(Task.scala:121) at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:402) at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:408) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) [2019-08-12T10:15:07.103Z] spark.org.apache.spark.executor.Executor ERROR: appId: 901C9278-B4E9-4EBB-AABF-8DB9C4DEF974, du: 1, message: Exception in task 1.0 in stage 37.0 (TID 2034) java.lang.NullPointerException at com.microsoft.ml.spark.TrainUtils$.networkInit(TrainUtils.scala:275) at com.microsoft.ml.spark.TrainUtils$.trainLightGBM(TrainUtils.scala:313) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:188) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:185) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90) at org.apache.spark.scheduler.Task.run(Task.scala:121) at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:402) at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:408) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748) [2019-08-12T10:15:07.427Z] spark.org.apache.spark.executor.Executor ERROR: appId: 901C9278-B4E9-4EBB-AABF-8DB9C4DEF974, du: 1, message: Exception in task 2.0 in stage 37.0 (TID 2037) java.net.ConnectException: Connection refused (Connection refused) at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at java.net.Socket.connect(Socket.java:538) at java.net.Socket.<init>(Socket.java:434) at java.net.Socket.<init>(Socket.java:211) at com.microsoft.ml.spark.TrainUtils$.getNetworkInitNodes(TrainUtils.scala:240) at com.microsoft.ml.spark.TrainUtils$$anonfun$7.apply(TrainUtils.scala:303) at com.microsoft.ml.spark.TrainUtils$$anonfun$7.apply(TrainUtils.scala:298) at com.microsoft.ml.spark.StreamUtilities$.using(StreamUtilities.scala:29) at com.microsoft.ml.spark.TrainUtils$.trainLightGBM(TrainUtils.scala:297) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at com.microsoft.ml.spark.LightGBMBase$$anonfun$4.apply(LightGBMBase.scala:49) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:188) at org.apache.spark.sql.execution.MapPartitionsExec$$anonfun$5.apply(objects.scala:185) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:836) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:52) at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:324) at org.apache.spark.rdd.RDD.iterator(RDD.scala:288) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:90) at org.apache.spark.scheduler.Task.run(Task.scala:121) at org.apache.spark.executor.Executor$TaskRunner$$anonfun$10.apply(Executor.scala:402) at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1360) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:408) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)