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Getting non-traceable NullPointerExceptions

alhuelamo
New Contributor II

โ€Ž12-07-2022 08:14 AM

We're running a job that's issuing NullPointerException without traces of our job's code.

Does anybody know what would be the best course of action when it comes to debugging these issues?

The job is a Scala job running on DBR 11.3 LTS.

In case it's related with the issue, the job targets both AWS S3 and AWS Redshift for I/O.

Here's one of the stack traces

Job aborted due to stage failure: Task 267 in stage 30.0 failed 4 times, most recent failure: Lost task 267.3 in stage 30.0 (TID 6343) (10.218.226.53 executor 2): java.lang.NullPointerException
	at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
 
Driver stacktrace:
Caused by: NullPointerException: 
at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)
 
Driver stacktrace:
	at org.apache.spark.scheduler.DAGScheduler.failJobAndIndependentStages(DAGScheduler.scala:3312)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2(DAGScheduler.scala:3244)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2$adapted(DAGScheduler.scala:3235)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
	at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:3235)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1(DAGScheduler.scala:1424)
	at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1$adapted(DAGScheduler.scala:1424)
	at scala.Option.foreach(Option.scala:407)
	at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:1424)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:3524)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:3462)
	at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:3450)
	at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:51)
Caused by: java.lang.NullPointerException
	at org.apache.spark.unsafe.map.BytesToBytesMap.safeLookup(BytesToBytesMap.java:534)
	at org.apache.spark.sql.execution.joins.UnsafeHashedRelation.get(HashedRelation.scala:231)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.hashAgg_doAggregateWithKeys_0$(Unknown Source)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIteratorForCodegenStage2.processNext(Unknown Source)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anon$1.hasNext(WholeStageCodegenExec.scala:761)
	at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:460)
	at org.apache.spark.shuffle.sort.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:195)
	at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$3(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.$anonfun$runTask$1(ShuffleMapTask.scala:81)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:53)
	at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
	at org.apache.spark.scheduler.Task.doRunTask(Task.scala:169)
	at org.apache.spark.scheduler.Task.$anonfun$run$4(Task.scala:137)
	at com.databricks.unity.EmptyHandle$.runWithAndClose(UCSHandle.scala:104)
	at org.apache.spark.scheduler.Task.$anonfun$run$1(Task.scala:137)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.scheduler.Task.run(Task.scala:96)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$13(Executor.scala:902)
	at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1696)
	at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$4(Executor.scala:905)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at com.databricks.spark.util.ExecutorFrameProfiler$.record(ExecutorFrameProfiler.scala:110)
	at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:760)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:750)

4 REPLIES 4

UmaMahesh1
Honored Contributor III

โ€Ž12-07-2022 09:15 AM

NullPointerException will occur when you are accessing an instance method or if you are trying to access elements in a null array or you are calling a method on an object referred by null value.

To give you suggestion on how to avoid that, we might need to know what exactly you are doing and if you are calling methods on null referred values if any.

Uma Mahesh D
0 Kudos

alhuelamo
New Contributor II
In response to UmaMahesh1

โ€Ž12-07-2022 09:25 AM

Hi @Uma Maheswara Rao Desulaโ€‹, thanks for your answer.

You're right, NullPointerExceptions occur whenever we try to access some null values; but in this case, by looking at the stack trace, there is nothing that points me to my own code. It's just Spark internals I have no control over. This makes me think there is some kind of underlying cause for this issue, but without more specific clues it's being very difficult to track.

0 Kudos

UmaMahesh1
Honored Contributor III
In response to alhuelamo

โ€Ž12-07-2022 09:32 AM

That's the thing with NullPointerExceptions unfortunately. As per my experience, It won't point you the exact place where the exception is being raised. I had to look at all the previous methods being called and check if null value is being referenced to fix this issue.

The chances to debug in a different way is very less. Let's see if the community comes up with an answer which might help.

Uma Mahesh D
0 Kudos

-werners-
Esteemed Contributor III
In response to alhuelamo

โ€Ž12-08-2022 06:57 AM

Agree.

so commenting out code and see if you get the exception. if not: exception is raised in the commented part. if yes: repeat.

0 Kudos

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