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https://issues.apache.org/jira/browse/FLINK-6115?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15940101#comment-15940101
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Luke Hutchison commented on FLINK-6115:
---------------------------------------
Hi [~fhueske]],
So the wire format of individual serialized objects cannot be touched, but is
there no version code or magic number at the beginning of savepoint files? If
there is currently no magic number or version code, there should be one, for
exactly this reason!
You could add a magic number and serialization number to the beginning of
future savepoint files, with only a vanishingly small chance of spurious
collision with legitimate values if these numbers are looked for in the first
couple of words of existing savepoint files, assuming you only need backwards
compatibility, not also forwards compatibility. Then you would be free to use
different serializers depending on the wire format version.
If this is not done, then the Tuple constructors should probably throw
NullPointerExceptions for now, until this is fixed. This is clearly not
desirable, as not all tuples will be serialized -- but my point was that the
user can't even predict or control when tuples are serialized, so this should
probably be enforced at the point where the problem is introduced, and not
later when the Flink runtime decides to serialize a tuple without the context
that caused the problem being available.
> Need more helpful error message when trying to serialize a tuple with a null
> field
> ----------------------------------------------------------------------------------
>
> Key: FLINK-6115
> URL: https://issues.apache.org/jira/browse/FLINK-6115
> Project: Flink
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.2.0
> Reporter: Luke Hutchison
>
> When Flink tries to serialize a tuple with a null field, you get the
> following, which has no information about where in the program the problem
> occurred (all the stack trace lines are in Flink, not in user code).
> {noformat}
> Exception in thread "main"
> org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
> at
> org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply$mcV$sp(JobManager.scala:900)
> at
> org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:843)
> at
> org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:843)
> at
> scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
> at
> scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
> at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
> at
> akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:397)
> at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
> at
> scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
> at
> scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
> at
> scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
> Caused by: java.lang.IllegalArgumentException: The record must not be null.
> at
> org.apache.flink.api.common.typeutils.base.array.StringArraySerializer.serialize(StringArraySerializer.java:73)
> at
> org.apache.flink.api.common.typeutils.base.array.StringArraySerializer.serialize(StringArraySerializer.java:33)
> at
> org.apache.flink.api.java.typeutils.runtime.TupleSerializer.serialize(TupleSerializer.java:124)
> at
> org.apache.flink.api.java.typeutils.runtime.TupleSerializer.serialize(TupleSerializer.java:30)
> at
> org.apache.flink.runtime.plugable.SerializationDelegate.write(SerializationDelegate.java:56)
> at
> org.apache.flink.runtime.io.network.api.serialization.SpanningRecordSerializer.addRecord(SpanningRecordSerializer.java:77)
> at
> org.apache.flink.runtime.io.network.api.writer.RecordWriter.sendToTarget(RecordWriter.java:113)
> at
> org.apache.flink.runtime.io.network.api.writer.RecordWriter.emit(RecordWriter.java:88)
> at
> org.apache.flink.runtime.operators.shipping.OutputCollector.collect(OutputCollector.java:65)
> at
> org.apache.flink.runtime.operators.util.metrics.CountingCollector.collect(CountingCollector.java:35)
> at
> org.apache.flink.runtime.operators.chaining.ChainedMapDriver.collect(ChainedMapDriver.java:79)
> at
> org.apache.flink.runtime.operators.util.metrics.CountingCollector.collect(CountingCollector.java:35)
> at
> org.apache.flink.api.java.operators.translation.PlanFilterOperator$FlatMapFilter.flatMap(PlanFilterOperator.java:51)
> at
> org.apache.flink.runtime.operators.FlatMapDriver.run(FlatMapDriver.java:108)
> at org.apache.flink.runtime.operators.BatchTask.run(BatchTask.java:490)
> at
> org.apache.flink.runtime.operators.BatchTask.invoke(BatchTask.java:355)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:655)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> The only thing I can tell from this is that it happened somewhere in a
> flatMap (but I have dozens of them in my code). Surely there's a way to pull
> out the source file name and line number from the program DAG node when
> errors like this occur?
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