Why accesing DataFrame from UDF results in NullPointerException?

Question

I have a problem executing a Spark application.

Source code:

// Read table From HDFS
val productInformation = spark.table("temp.temp_table1")
val dict = spark.table("temp.temp_table2")

// Custom UDF
val countPositiveSimilarity = udf[Long, Seq[String], Seq[String]]((a, b) => 
    dict.filter(
        (($"first".isin(a: _*) && $"second".isin(b: _*)) || ($"first".isin(b: _*) && $"second".isin(a: _*))) && $"similarity" > 0.7
    ).count
)

val result = productInformation.withColumn("positive_count", countPositiveSimilarity($"title", $"internal_category"))

// Error occurs!
result.show

Error message:

org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 54.0 failed 4 times, most recent failure: Lost task 0.3 in stage 54.0 (TID 5887, ip-10-211-220-33.ap-northeast-2.compute.internal, executor 150): org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1: (array<string>, array<string>) => bigint)
    at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
    at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
    at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:377)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:231)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:225)
    at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
    at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
    at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
    at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
    at org.apache.spark.scheduler.Task.run(Task.scala:99)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:282)
    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:745)
Caused by: java.lang.NullPointerException
    at $anonfun$1.apply(<console>:45)
    at $anonfun$1.apply(<console>:43)
    ... 16 more

Driver stacktrace:
  at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1435)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1423)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1422)
  at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
  at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
  at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1422)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:802)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:802)
  at scala.Option.foreach(Option.scala:257)
  at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:802)
  at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1650)
  at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1605)
  at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1594)
  at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
  at org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:628)
  at org.apache.spark.SparkContext.runJob(SparkContext.scala:1918)
  at org.apache.spark.SparkContext.runJob(SparkContext.scala:1931)
  at org.apache.spark.SparkContext.runJob(SparkContext.scala:1944)
  at org.apache.spark.sql.execution.SparkPlan.executeTake(SparkPlan.scala:333)
  at org.apache.spark.sql.execution.CollectLimitExec.executeCollect(limit.scala:38)
  at org.apache.spark.sql.Dataset$$anonfun$org$apache$spark$sql$Dataset$$execute$1$1.apply(Dataset.scala:2371)
  at org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:57)
  at org.apache.spark.sql.Dataset.withNewExecutionId(Dataset.scala:2765)
  at org.apache.spark.sql.Dataset.org$apache$spark$sql$Dataset$$execute$1(Dataset.scala:2370)
  at org.apache.spark.sql.Dataset.org$apache$spark$sql$Dataset$$collect(Dataset.scala:2377)
  at org.apache.spark.sql.Dataset$$anonfun$head$1.apply(Dataset.scala:2113)
  at org.apache.spark.sql.Dataset$$anonfun$head$1.apply(Dataset.scala:2112)
  at org.apache.spark.sql.Dataset.withTypedCallback(Dataset.scala:2795)
  at org.apache.spark.sql.Dataset.head(Dataset.scala:2112)
  at org.apache.spark.sql.Dataset.take(Dataset.scala:2327)
  at org.apache.spark.sql.Dataset.showString(Dataset.scala:248)
  at org.apache.spark.sql.Dataset.show(Dataset.scala:636)
  at org.apache.spark.sql.Dataset.show(Dataset.scala:595)
  at org.apache.spark.sql.Dataset.show(Dataset.scala:604)
  ... 48 elided
Caused by: org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1: (array<string>, array<string>) => bigint)
  at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
  at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
  at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:377)
  at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:231)
  at org.apache.spark.sql.execution.SparkPlan$$anonfun$2.apply(SparkPlan.scala:225)
  at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
  at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$25.apply(RDD.scala:826)
  at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
  at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
  at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
  at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
  at org.apache.spark.scheduler.Task.run(Task.scala:99)
  at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:282)
  ... 3 more
Caused by: java.lang.NullPointerException
  at $anonfun$1.apply(<console>:45)
  at $anonfun$1.apply(<console>:43)
  ... 16 more

I have checked whether productInformation and dict have null value in Columns. But there are no null values.

Can anyone help me? I attached example code to let you know more details:

case class Target(wordListOne: Seq[String], WordListTwo: Seq[String])
val targetData = Seq(Target(Seq("Spark", "Wrong", "Something"), Seq("Java", "Grape", "Banana")),
                     Target(Seq("Java", "Scala"), Seq("Scala", "Banana")),
                     Target(Seq(""), Seq("Grape", "Banana")),
                     Target(Seq(""), Seq("")))
val targets = spark.createDataset(targetData)

case class WordSimilarity(first: String, second: String, similarity: Double)
val similarityData = Seq(WordSimilarity("Spark", "Java", 0.8), 
                     WordSimilarity("Scala", "Spark", 0.9), 
                     WordSimilarity("Java", "Scala", 0.9),
                     WordSimilarity("Apple", "Grape", 0.66),
                     WordSimilarity("Scala", "Apple", -0.1),
                     WordSimilarity("Gine", "Spark", 0.1)) 
val dict = spark.createDataset(similarityData)

val countPositiveSimilarity = udf[Long, Seq[String], Seq[String]]((a, b) => 
    dict.filter(
        (($"first".isin(a: _*) && $"second".isin(b: _*)) || ($"first".isin(b: _*) && $"second".isin(a: _*))) && $"similarity" > 0.7
    ).count
)

val countDF = targets.withColumn("positive_count", countPositiveSimilarity($"wordListOne", $"wordListTwo"))

This is an example code and is similar to my original code. Example code operates well. Which point should I check in original code and data?

Answer 1

Very interesting question. I have to do some search, and here is my though. Hope this will help you a little bit.

When you create Dataset via createDataset, spark will assign this dataset with LocalRelation logical query plan.

def createDataset[T : Encoder](data: Seq[T]): Dataset[T] = {
    val enc = encoderFor[T]
    val attributes = enc.schema.toAttributes
    val encoded = data.map(d => enc.toRow(d).copy())
    val plan = new LocalRelation(attributes, encoded)
    Dataset[T](self, plan)
  }

Follow this link: LocalRelation is a leaf logical plan that allow functions like collect or take to be executed locally, i.e. without using Spark executors.

And, it's true as isLocal method point out

 /**
   * Returns true if the `collect` and `take` methods can be run locally
   * (without any Spark executors).
   *
   * @group basic
   * @since 1.6.0
   */
  def isLocal: Boolean = logicalPlan.isInstanceOf[LocalRelation]

Obviously, You can check out your 2 datasets is local.

And, the show method actually call take internally.

private[sql] def showString(_numRows: Int, truncate: Int = 20): String = {
    val numRows = _numRows.max(0)
    val takeResult = toDF().take(numRows + 1)
    val hasMoreData = takeResult.length > numRows
    val data = takeResult.take(numRows)

So, with those envidences, I think the call countDF.show is executed, it will behave simliar as when you call count on dict dataset from driver, number of call times is number of records of targets. And, the dict dataset of course doesn't need to be local for the show on countDF work.

You can try to save countDF, it will give you exception same as first case org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1: (array<string>, array<string>) => bigint)

Answer 2

You can not use a Dataframe inside of an udf. You will need to join productInformation and dict, and do the udf logic after the join.