Minor Description
I don't have a minimal reproducible example yet, sorry. I have the following lines in a unit test for our Spark application:
val df = mySparkSession.read.format("jdbc") .options(Map("url" -> url, "dbtable" -> "test_table")) .load() df.show println(df.rdd.collect)
The output shows the DataFrame contents from df.show. But the collect fails:
org.apache.spark.SparkException: Job aborted due to stage failure: Task serialization failed: java.util.NoSuchElementException: None.get java.util.NoSuchElementException: None.get at scala.None$.get(Option.scala:347) at scala.None$.get(Option.scala:345) at org.apache.spark.sql.execution.DataSourceScanExec$class.org$apache$spark$sql$execution$DataSourceScanExec$$redact(DataSourceScanExec.scala:70) at org.apache.spark.sql.execution.DataSourceScanExec$$anonfun$4.apply(DataSourceScanExec.scala:54) at org.apache.spark.sql.execution.DataSourceScanExec$$anonfun$4.apply(DataSourceScanExec.scala:52) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234) at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59) at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48) at scala.collection.TraversableLike$class.map(TraversableLike.scala:234) at scala.collection.AbstractTraversable.map(Traversable.scala:104) at org.apache.spark.sql.execution.DataSourceScanExec$class.simpleString(DataSourceScanExec.scala:52) at org.apache.spark.sql.execution.RowDataSourceScanExec.simpleString(DataSourceScanExec.scala:75) at org.apache.spark.sql.catalyst.plans.QueryPlan.verboseString(QueryPlan.scala:349) at org.apache.spark.sql.execution.RowDataSourceScanExec.org$apache$spark$sql$execution$DataSourceScanExec$$super$verboseString(DataSourceScanExec.scala:75) at org.apache.spark.sql.execution.DataSourceScanExec$class.verboseString(DataSourceScanExec.scala:60) at org.apache.spark.sql.execution.RowDataSourceScanExec.verboseString(DataSourceScanExec.scala:75) at org.apache.spark.sql.catalyst.trees.TreeNode.generateTreeString(TreeNode.scala:556) at org.apache.spark.sql.execution.WholeStageCodegenExec.generateTreeString(WholeStageCodegenExec.scala:451) at org.apache.spark.sql.catalyst.trees.TreeNode.generateTreeString(TreeNode.scala:576) at org.apache.spark.sql.catalyst.trees.TreeNode.treeString(TreeNode.scala:480) at org.apache.spark.sql.catalyst.trees.TreeNode.treeString(TreeNode.scala:477) at org.apache.spark.sql.catalyst.trees.TreeNode.toString(TreeNode.scala:474) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1421) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at scala.collection.immutable.List$SerializationProxy.writeObject(List.scala:468) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1028) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at org.apache.spark.serializer.JavaSerializationStream.writeObject(JavaSerializer.scala:43) at org.apache.spark.serializer.JavaSerializerInstance.serialize(JavaSerializer.scala:100) at org.apache.spark.scheduler.DAGScheduler.submitMissingTasks(DAGScheduler.scala:1003) at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$submitStage(DAGScheduler.scala:930) at org.apache.spark.scheduler.DAGScheduler.handleJobSubmitted(DAGScheduler.scala:874) at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1677) at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1669) at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1658) at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
Looks like this is due to https://github.com/apache/spark/commit/91fa80fe8a2480d64c430bd10f97b3d44c007bcc#diff-2a91a9a59953aa82fa132aaf45bd731bR69 from https://issues.apache.org/jira/browse/SPARK-20070. It tries to redact sensitive information from explain output. (We are not trying to explain anything here, so I doubt it is meant to be running in this case.) When it needs to access some configuration, it tries to take it from the "current" Spark session, which it just reads from a thread-local variable. We appear to be on a thread where this variable is not set.
My impression is that SPARK-20070 unintentionally introduced a very hard constraint on multi-threaded Spark applications.
