Connection pool is not yet initialized.(name:'default)

[WARN] [TaskSetManager] Lost task 0.1 in stage 23.0 (TID 75, ip-172-31-105-42.ap-southeast-1.compute.internal): java.lang.IllegalStateException: Connection pool is not yet initialized.(name:'default)
        at scalikejdbc.ConnectionPool$$anonfun$get$1.apply(ConnectionPool.scala:76)
        at scalikejdbc.ConnectionPool$$anonfun$get$1.apply(ConnectionPool.scala:74)
        at scala.collection.MapLike$class.getOrElse(MapLike.scala:128)
        at scala.collection.AbstractMap.getOrElse(Map.scala:58)
        at scalikejdbc.ConnectionPool$.get(ConnectionPool.scala:74)
        at scalikejdbc.ConnectionPool$.apply(ConnectionPool.scala:65)
        at scalikejdbc.DB$.connectionPool(DB.scala:152)
        at scalikejdbc.DB$.localTx(DB.scala:262)
        at org.apache.predictionio.data.storage.jdbc.JDBCPEvents$$anonfun$delete$1$$anonfun$apply$11.apply(JDBCPEvents.scala:182)
        at org.apache.predictionio.data.storage.jdbc.JDBCPEvents$$anonfun$delete$1$$anonfun$apply$11.apply(JDBCPEvents.scala:181)
        at scala.collection.Iterator$class.foreach(Iterator.scala:727)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
        at org.apache.predictionio.data.storage.jdbc.JDBCPEvents$$anonfun$delete$1.apply(JDBCPEvents.scala:181)
        at org.apache.predictionio.data.storage.jdbc.JDBCPEvents$$anonfun$delete$1.apply(JDBCPEvents.scala:179)
        at org.apache.spark.rdd.RDD$$anonfun$foreachPartition$1$$anonfun$apply$33.apply(RDD.scala:920)
        at org.apache.spark.rdd.RDD$$anonfun$foreachPartition$1$$anonfun$apply$33.apply(RDD.scala:920)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
        at org.apache.spark.scheduler.Task.run(Task.scala:89)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:227)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:748)

PIO_STORAGE_REPOSITORIES_METADATA_NAME=pio_meta
PIO_STORAGE_SOURCES_ELASTICSEARCH_HOME=/elasticsearch
PIO_STORAGE_REPOSITORIES_EVENTDATA_NAME=pio_event
PIO_STORAGE_SOURCES_PGSQL_INDEX=enabled
PIO_STORAGE_REPOSITORIES_EVENTDATA_SOURCE=PGSQL
PIO_STORAGE_SOURCES_ELASTICSEARCH_TYPE=elasticsearch
PIO_STORAGE_SOURCES_ELASTICSEARCH_PORTS=9300
PIO_STORAGE_REPOSITORIES_METADATA_SOURCE=ELASTICSEARCH
PIO_STORAGE_REPOSITORIES_MODELDATA_NAME=pio_model
PIO_HOME=/PredictionIO
PIO_STORAGE_SOURCES_PGSQL_USERNAME=dbuser
PIO_STORAGE_REPOSITORIES_MODELDATA_SOURCE=PGSQL
PIO_STORAGE_SOURCES_PGSQL_URL=jdbc:postgresql://hostname:5432/predictionio
PIO_STORAGE_SOURCES_ELASTICSEARCH_HOSTS=es-hostname
PIO_STORAGE_SOURCES_ELASTICSEARCH_CLUSTERNAME=es_cluster
PIO_STORAGE_SOURCES_PGSQL_TYPE=jdbc
PIO_STORAGE_SOURCES_PGSQL_PASSWORD=xxxxxxxxxxxxxx