Scala 为什么从UDF访问DataFrame会导致NullPointerException?
我在执行Spark应用程序时遇到问题 源代码:Scala 为什么从UDF访问DataFrame会导致NullPointerException?,scala,apache-spark,Scala,Apache Spark,我在执行Spark应用程序时遇到问题 源代码: // 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) => dic
// 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", $"internal_category"))
// Error occurs!
result.show
错误消息:
org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 54.0 failed 4 times, most recent failure: Lost task 0.3 in stage 54.0 (TID 5887, ip-10-211-220-33.ap-northeast-2.compute.internal, executor 150): org.apache.spark.SparkException: Failed to execute user defined function($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$1.apply(<console>:43)
... 16 more
这是一个示例代码,与我的原始代码类似。
示例代码运行良好。我应该在哪个点签入原始代码和数据?您不能在
udf
内部使用Dataframe
。您需要加入productInformation
和dict
,并在加入后执行udf
逻辑。非常有趣的问题。我必须做一些搜索,这是我的想法。希望这能对你有所帮助
当您通过创建数据集
时,spark将为该数据集分配本地关系
逻辑查询计划
def createDataset[T : Encoder](data: Seq[T]): Dataset[T] = {
val enc = encoderFor[T]
val attributes = enc.schema.toAttributes
val encoded = data.map(d => enc.toRow(d).copy())
val plan = new LocalRelation(attributes, encoded)
Dataset[T](self, plan)
}
遵循以下步骤:
LocalRelation是一种叶逻辑计划,允许在本地执行collect或take等函数,即不使用Spark执行器。
正如方法所指出的,这是真的
/**
* Returns true if the `collect` and `take` methods can be run locally
* (without any Spark executors).
*
* @group basic
* @since 1.6.0
*/
def isLocal: Boolean = logicalPlan.isInstanceOf[LocalRelation]
显然,您可以检查您的两个数据集是否为本地数据集
而且,该方法实际上在内部调用take
private[sql] def showString(_numRows: Int, truncate: Int = 20): String = {
val numRows = _numRows.max(0)
val takeResult = toDF().take(numRows + 1)
val hasMoreData = takeResult.length > numRows
val data = takeResult.take(numRows)
因此,在这些情况下,我认为执行调用countDF.show
时,它的行为将类似于从driver调用dict
数据集上的count
,调用次数是目标的记录数。当然,dict
数据集对于countDF
工作的显示不需要是本地的
您可以尝试保存countDF
,它将为您提供与第一种情况相同的异常
org.apache.spark.sparkeexception:无法执行用户定义的函数($anonfun$1:(数组,数组)=>bigint)
是否可以在UDF中使用dict(数据帧)转换的不可变映射?目前,很难加入productInformation和dict。如果dict
df不是太大,您可以收集它,转换为映射,然后在UDF中使用该映射以获得答案。我有两个问题。1) 您的主要观点是,换句话说,当我执行save或show方法时,示例代码中将出现错误?我是入门级Spark用户,所以我认为这可能是一个愚蠢的问题。2) 除此之外,没有办法在udf?1中使用数据帧。你的第一个案例,两个都会失败。第二种情况下,save将失败。2.数据集可以是udf格式,也就是说,可以很好地编译。但是,如果调用的数据集不是本地的,并且操作不是take
或collect
,那么它将在运行时像第一种情况一样失败。
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)