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https://issues.apache.org/jira/browse/KAFKA-8884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16953455#comment-16953455
]
ASF GitHub Bot commented on KAFKA-8884:
---------------------------------------
mjsax commented on pull request #7309: KAFKA-8884: class cast exception
improvement
URL: https://github.com/apache/kafka/pull/7309
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> Improve streams errors on class cast exception in ProcessorsNodes
> -----------------------------------------------------------------
>
> Key: KAFKA-8884
> URL: https://issues.apache.org/jira/browse/KAFKA-8884
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: Antony Stubbs
> Assignee: Antony Stubbs
> Priority: Minor
>
> [https://github.com/apache/kafka/pull/7309]
>
> If a processor causes a class cast exception, atm you get a bit of a cryptic
> error if you're not used to them, and without a context sensitive suggestion
> as to what could be wrong. Often these can be cause by missconfigured Serdes
> (defaults).
>
> As an example of the improvement over the case exception:
> {{{{ }}{{org.apache.kafka.streams.errors.StreamsException: Exception caught
> in process. taskId=0_0, processor=KSTREAM-SOURCE-0000000000,
> topic=streams-plaintext-input, partition=0, offset=0,
> stacktrace=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. Deserialized
> input types are: key: [B, value: [B}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:123)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:201)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:180)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:133)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:87)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:366)}}}}
> \{{ {{ at
> org.apache.kafka.streams.TopologyTestDriver.pipeInput(TopologyTestDriver.java:419)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorNodeTest.testTopologyLevelClassCastException(ProcessorNodeTest.java:176)}}}}
> \{{ {{ at
> java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native
> Method)}}}}
> \{{ {{ at
> java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)}}}}
> \{{ {{ at
> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)}}}}
> \{{ {{ at java.base/java.lang.reflect.Method.invoke(Method.java:566)}}}}
> \{{ {{ at
> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)}}}}
> \{{ {{ at
> org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)}}}}
> \{{ {{ at
> org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)}}}}
> \{{ {{ at
> org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)}}}}
> \{{ {{ at
> org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:305)}}}}
> \{{ {{ at
> org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)}}}}
> \{{ {{ at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:365)}}}}
> \{{ {{ at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)}}}}
> \{{ {{ at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)}}}}
> \{{ {{ at org.junit.runners.ParentRunner$4.run(ParentRunner.java:330)}}}}
> \{{ {{ at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:78)}}}}
> \{{ {{ at
> org.junit.runners.ParentRunner.runChildren(ParentRunner.java:328)}}}}
> \{{ {{ at org.junit.runners.ParentRunner.access$100(ParentRunner.java:65)}}}}
> \{{ {{ at
> org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:292)}}}}
> \{{ {{ at
> org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:305)}}}}
> \{{ {{ at org.junit.runners.ParentRunner.run(ParentRunner.java:412)}}}}
> \{{ {{ at org.junit.runner.JUnitCore.run(JUnitCore.java:137)}}}}
> \{{ {{ at
> com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)}}}}
> \{{ {{ at
> com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)}}}}
> \{{ {{ at
> com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)}}}}
> \{{ {{ at
> com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)}}}}
> \{{ {{ Caused by: java.lang.ClassCastException: class [B cannot be cast to
> class java.lang.String ([B and java.lang.String are in module java.base of
> loader 'bootstrap')}}}}
> \{{ {{ at
> org.apache.kafka.streams.kstream.internals.AbstractStream.lambda$withKey$1(AbstractStream.java:103)}}}}
> \{{ {{ at
> org.apache.kafka.streams.kstream.internals.KStreamFlatMapValues$KStreamFlatMapValuesProcessor.process(KStreamFlatMapValues.java:40)}}}}
> \{{ {{ at
> org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:119)}}}}
> {{ {
> { ... 32 more}
> }}}
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