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Posted to jira@kafka.apache.org by "A. Sophie Blee-Goldman (Jira)" <ji...@apache.org> on 2021/09/08 02:49:00 UTC
[jira] [Commented] (KAFKA-12963) Improve error message for Class
cast exception
[ https://issues.apache.org/jira/browse/KAFKA-12963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17411644#comment-17411644 ]
A. Sophie Blee-Goldman commented on KAFKA-12963:
------------------------------------------------
{quote}I can imagine that a class cast exception of types A and B for processor KSTREAM-TRANSFORM-0000000016 would be a bit of a head-scratcher
{quote}
Very fair, that's why we recommend naming all operators ;) . But you should be able to figure out what it is from the topology description if necessary, along with the upstream topics. I know it's not the best experience but I think trying to put the topic into this message would end up with a lot of checking specific topological patterns in a way that would be hard not to accidentally mess up when changing things in the future. Still, if you'd like to have a crack at it yourself then definitely go for it! Otherwise maybe split that into a separate feature request ticket and see if someone else does
> Improve error message for Class cast exception
> ----------------------------------------------
>
> Key: KAFKA-12963
> URL: https://issues.apache.org/jira/browse/KAFKA-12963
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Affects Versions: 2.7.0
> Reporter: Rasmus Helbig Hansen
> Assignee: Andrew Lapidas
> Priority: Minor
> Fix For: 3.1.0
>
>
> After a topology change and starting the application again, we got this type of error message:
> [g9z-StreamThread-1] ERROR org.apache.kafka.streams.processor.internals.TaskManager - stream-thread [g9z-StreamThread-1] Failed to process stream task 1_12 due to the following error:
> org.apache.kafka.streams.errors.StreamsException: ClassCastException invoking Processor. Do the Processor's input types match the deserialized types? Check the Serde setup and change the default Serdes in StreamConfig or provide correct Serdes via method parameters. Make sure the Processor can accept the deserialized input of type key: org.acme.SomeKey, and value: org.acme.SomeValue.
> Note that although incorrect Serdes are a common cause of error, the cast exception might have another cause (in user code, for example). For example, if a processor wires in a store, but casts the generics incorrectly, a class cast exception could be raised during processing, but the cause would not be wrong Serdes.
> at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:185)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:273)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:252)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:219)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:172)
> at org.apache.kafka.streams.kstream.internals.KStreamJoinWindow$KStreamJoinWindowProcessor.process(KStreamJoinWindow.java:55)
> at org.apache.kafka.streams.processor.internals.ProcessorAdapter.process(ProcessorAdapter.java:71)
> at org.apache.kafka.streams.processor.internals.ProcessorNode.lambda$process$2(ProcessorNode.java:181)
> at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)
> at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:181)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forwardInternal(ProcessorContextImpl.java:273)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:252)
> at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:219)
> at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:86)
> at org.apache.kafka.streams.processor.internals.StreamTask.lambda$process$1(StreamTask.java:703)
> at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)
> at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:703)
> at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:1105)
> at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:647)
> at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:553)
> at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:512)
> Caused by: java.lang.ClassCastException: class org.acme.SomeValue cannot be cast to class org.acme.OtherValue (org.acme.SomeValue and org.acme.OtherValue are in unnamed module of loader 'app')
> at org.apache.kafka.streams.kstream.internals.KStreamKStreamJoin$KStreamKStreamJoinProcessor.process(KStreamKStreamJoin.java:112)
> at org.apache.kafka.streams.processor.internals.ProcessorAdapter.process(ProcessorAdapter.java:71)
> at org.apache.kafka.streams.processor.internals.ProcessorNode.lambda$process$2(ProcessorNode.java:181)
> at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:883)
> at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:181)
> ... 20 more
> [g9z-StreamThread-1] ERROR org.apache.kafka.streams.processor.internals.StreamThread - stream-thread [g9z-StreamThread-1] Encountered the following exception during processing and the thread is going to shut down:
> org.apache.kafka.streams.errors.StreamsException: ClassCastException invoking Processor. Do the Processor's input types match the deserialized types? Check the Serde setup and change the default Serdes in StreamConfig or provide correct Serdes via method parameters. Make sure the Processor can accept the deserialized input of type key: org.acme.SomeKey, and value: org.acme.SomeValue.
> Note that although incorrect Serdes are a common cause of error, the cast exception might have another cause (in user code, for example). For example, if a processor wires in a store, but casts the generics incorrectly, a class cast exception could be raised during processing, but the cause would not be wrong Serdes.
>
> It doesn't give enough context, like processor name and topic, which made troubleshooting unnecessary tricky.
>
> Very similar to KAFKA-8884 which was fixed in 2.4.0. It seems like a regression.
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