Scala 如何在Spark中强制执行数据帧求值
有时(例如,对于测试和bechmarking),我希望强制执行在数据帧上定义的转换。调用像Scala 如何在Spark中强制执行数据帧求值,scala,apache-spark,Scala,Apache Spark,有时(例如,对于测试和bechmarking),我希望强制执行在数据帧上定义的转换。调用像count这样的操作并不确保所有列都实际计算,show只能计算所有行的子集(参见下面的示例) 我的解决方案是使用df.write.saveAsTable将DataFrame写入HDFS,但这会使我的系统与我不想再保留的表“混乱” 那么,触发数据帧评估的最佳方法是什么呢 编辑: 请注意,最近还讨论了spark开发者列表: 我举了一个小例子,说明DataFrame上的count不能评估所有内容(使用Spark
count
这样的操作并不确保所有列都实际计算,show
只能计算所有行的子集(参见下面的示例)
我的解决方案是使用df.write.saveAsTable
将DataFrame
写入HDFS,但这会使我的系统与我不想再保留的表“混乱”
那么,触发数据帧评估的最佳方法是什么呢
编辑:
请注意,最近还讨论了spark开发者列表:
我举了一个小例子,说明DataFrame
上的count
不能评估所有内容(使用Spark 1.6.3和Spark master=local[2]
进行测试):
使用相同的逻辑,这里有一个示例,show
不会计算所有行:
val df = sc.parallelize(1 to 10).toDF("id")
val myUDF = udf((i:Int) => {if(i==10) throw new RuntimeException;i})
df.withColumn("test",myUDF($"id")).show(5) // runs fine
df.withColumn("test",myUDF($"id")).show(10) // gives Exception
编辑2:对于Eliasah:例外说明如下:
org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 6.0 failed 1 times, most recent failure: Lost task 0.0 in stage 6.0 (TID 6, localhost): java.lang.RuntimeException
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply$mcII$sp(<console>:68)
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(<console>:68)
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(<console>:68)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)
at org.apache.spark.sql.execution.Project$$anonfun$1$$anonfun$apply$1.apply(basicOperators.scala:51)
at org.apache.spark.sql.execution.Project$$anonfun$1$$anonfun$apply$1.apply(basicOperators.scala:49)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
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Driver stacktrace:
at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1431)
at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1419)
at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1418)
at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1418)
at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
at scala.Option.foreach(Option.scala:236)
at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:799)
at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1640)
at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1599)
at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1588)
at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
at org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:620)
at org.apache.spark.SparkContext.runJob(SparkContext.scala:1832)
at org.apache.spark.SparkContext.runJob(SparkContext.scala:1845)
at org.apache.spark.SparkContext.runJob(SparkContext.scala:1858)
at org.apache.spark.sql.execution.SparkPlan.executeTake(SparkPlan.scala:212)
at org.apache.spark.sql.execution.Limit.executeCollect(basicOperators.scala:165)
at org.apache.spark.sql.execution.SparkPlan.executeCollectPublic(SparkPlan.scala:174)
at org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1500)
at org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1500)
at org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:56)
at org.apache.spark.sql.DataFrame.withNewExecutionId(DataFrame.scala:2087)
at org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$execute$1(DataFrame.scala:1499)
at org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$collect(DataFrame.scala:1506)
at org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1376)
at org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1375)
at org.apache.spark.sql.DataFrame.withCallback(DataFrame.scala:2100)
at org.apache.spark.sql.DataFrame.head(DataFrame.scala:1375)
at org.apache.spark.sql.DataFrame.take(DataFrame.scala:1457)
at org.apache.spark.sql.DataFrame.showString(DataFrame.scala:170)
at org.apache.spark.sql.DataFrame.show(DataFrame.scala:350)
at org.apache.spark.sql.DataFrame.show(DataFrame.scala:311)
at org.apache.spark.sql.DataFrame.show(DataFrame.scala:319)
at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:74)
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org.apache.spark.sparkeexception:作业因阶段失败而中止:阶段6.0中的任务0失败1次,最近的失败:阶段6.0中的任务0.0丢失(TID 6,localhost):java.lang.RuntimeException
在$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.申请$mcII$sp(:68)
在$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.申请(:68)
在$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$anonfun$1.申请(:68)
位于org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(未知源)
位于org.apache.spark.sql.execution.Project$$anonfun$1$$anonfun$apply$1.apply(basicOperators.scala:51)
位于org.apache.spark.sql.execution.Project$$anonfun$1$$anonfun$apply$1.apply(basicOperators.scala:49)
在scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
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驱动程序堆栈跟踪:
位于org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1431)
位于org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1419)
位于org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1418)
位于scala.collection.mutable.resizeblearray$class.foreach(resizeblearray.scala:59)
位于scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
位于org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1418)
位于org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
位于org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
位于scala.Option.foreach(Option.scala:236)
位于org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:799)
位于org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1640)
位于org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1599)
位于org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1588)
位于org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
位于org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:620)
位于org.apache.spark.SparkContext.runJob(SparkContext.scala:1832)
位于org.apache.spark.SparkContext.runJob(SparkContext.scala:1845)
位于org.apache.spark.SparkContext.runJob(SparkContext.scala:1858)
位于org.apache.spark.sql.execution.SparkPlan.executeTake(SparkPlan.scala:212)
位于org.apache.spark.sql.execution.Limit.executeCollect(basicOperators.scala:165)
位于org.apache.spark.sql.execution.SparkPlan.executeCollectPublic(SparkPlan.scala:174)
在org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1500)
在org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1500)
位于org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:56)
位于org.apache.spark.sql.DataFrame.withNewExecutionId(DataFrame.scala:2087)
位于org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$execute$1(DataFrame.scala:1499)
位于org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$collect(DataFrame.scala:1506)
位于org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1376)
位于org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1375)
位于org.apache.spark.sql.DataFrame.withCallback(DataFrame.scala:2100)
位于org.apache.spark.sql.DataFrame.head(DataFrame.scala:1375)
位于org.apache.spark.sql.DataFrame.take(DataFrame.scala:1457)
位于org.apache.spark.sql.DataFrame.showString(DataFrame.scala:170)
位于org.apache.spark.sql.DataFrame.show(DataFrame.scala:350)
位于org.apache.spark.sql.DataFrame.show(DataFrame.scala:311)
位于org.apache.spark.sql.DataFrame.show(DataFrame.scala:319)
在$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC。(:74)
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我想只要从DataFrame
获取一个底层的rdd
,并触发一个操作,就可以实现您想要的
df.withColumn("test",myUDF($"id")).rdd.count // this gives proper exceptions
看来,df.cache.count
是一条出路:
scala> val myUDF = udf((i:Int) => {if(i==1000) throw new RuntimeException;i})
myUDF: org.apache.spark.sql.expressions.UserDefinedFunction = UserDefinedFunction(<function1>,IntegerType,Some(List(IntegerType)))
scala> val df = sc.parallelize(1 to 1000).toDF("id")
df: org.apache.spark.sql.DataFrame = [id: int]
scala> df.withColumn("test",myUDF($"id")).show(10)
[rdd_51_0]
+---+----+
| id|test|
+---+----+
| 1| 1|
| 2| 2|
| 3| 3|
| 4| 4|
| 5| 5|
| 6| 6|
| 7| 7|
| 8| 8|
| 9| 9|
| 10| 10|
+---+----+
only showing top 10 rows
scala> df.withColumn("test",myUDF($"id")).count
res13: Long = 1000
scala> df.withColumn("test",myUDF($"id")).cache.count
org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1: (int) => int)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
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.
.
Caused by: java.lang.RuntimeException
scala>val myUDF=udf((i:Int)=>{if(i==1000)抛出新的RuntimeException;i})
myUDF:org.apache.spark.sql.expressions.UserDefinedFunction=UserDefinedFunction(,IntegerType,Some(List(IntegerType)))
scala>val df=sc.parallelize(1到1000).toDF(“id”)
df:org.apache.spark.sql.DataFrame=[id:int]
scala>df.withColumn(“测试”),myUDF($”i
scala> val myUDF = udf((i:Int) => {if(i==1000) throw new RuntimeException;i})
myUDF: org.apache.spark.sql.expressions.UserDefinedFunction = UserDefinedFunction(<function1>,IntegerType,Some(List(IntegerType)))
scala> val df = sc.parallelize(1 to 1000).toDF("id")
df: org.apache.spark.sql.DataFrame = [id: int]
scala> df.withColumn("test",myUDF($"id")).show(10)
[rdd_51_0]
+---+----+
| id|test|
+---+----+
| 1| 1|
| 2| 2|
| 3| 3|
| 4| 4|
| 5| 5|
| 6| 6|
| 7| 7|
| 8| 8|
| 9| 9|
| 10| 10|
+---+----+
only showing top 10 rows
scala> df.withColumn("test",myUDF($"id")).count
res13: Long = 1000
scala> df.withColumn("test",myUDF($"id")).cache.count
org.apache.spark.SparkException: Failed to execute user defined function($anonfun$1: (int) => int)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
.
.
.
Caused by: java.lang.RuntimeException