Apache kafka Kafka streams Ktable Ktable join在输出主题中不发出任何结果

我正在尝试在Scala中加入一个非常简单的Ktable-to-Ktable连接。两个主题都有一个分区，但我仍然没有看到任何关于“输出主题”的内容

object SimpleMerge extends App {
  val properties = KafkaProperties.get()

  val streamBuilder = new StreamsBuilder()

  val objectMetadataTable: KTable[Long, String] = streamBuilder.table("metadata-topic")

  val objectClassificationTable: KTable[Long, String] = streamBuilder.table("classification-topic")

  val objectClassificationWithMetadata: KTable[Long, String] = objectMetadataTable
    .join(objectClassificationTable, (metadata: String, classification: String) => metadata + classification)


  objectClassificationWithMetadata.toStream().to("output-topic")

  val kafkaStreams = new KafkaStreams(streamBuilder.build(), properties)
  kafkaStreams.cleanUp()
  kafkaStreams.start()

  Runtime.getRuntime.addShutdownHook(new Thread(() => {
    kafkaStreams.close()
  }))
}

我相信这是非常基本的，但我找不到任何线索。 注意：我可以看到两个输入主题都使用正确的相同键生成结果，因此已经排除了空键的问题

谢谢

例外情况

02:26:57.936 [MetadataClassificationMerger_1-757746d5-32e5-412b-934d-d29c1fc8c7a9-StreamThread-1] ERROR org.apache.kafka.streams.processor.internals.ProcessorStateManager - stream-thread [MetadataClassificationMerger_1-757746d5-32e5-412b-934d-d29c1fc8c7a9-StreamThread-1] task [0_0] Failed to flush state store metadata-topic-STATE-STORE-0000000000: 
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: [B, and value: org.apache.kafka.streams.kstream.internals.Change.
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:122) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:201) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:180) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.kstream.internals.TimestampedCacheFlushListener.apply(TimestampedCacheFlushListener.java:45) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.kstream.internals.TimestampedCacheFlushListener.apply(TimestampedCacheFlushListener.java:28) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.MeteredKeyValueStore.lambda$setFlushListener$1(MeteredKeyValueStore.java:227) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.CachingKeyValueStore.putAndMaybeForward(CachingKeyValueStore.java:92) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.CachingKeyValueStore.lambda$initInternal$0(CachingKeyValueStore.java:72) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:151) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:109) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.ThreadCache.flush(ThreadCache.java:124) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.CachingKeyValueStore.flush(CachingKeyValueStore.java:272) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.WrappedStateStore.flush(WrappedStateStore.java:84) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.state.internals.MeteredKeyValueStore.flush(MeteredKeyValueStore.java:333) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.ProcessorStateManager.flush(ProcessorStateManager.java:276) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.AbstractTask.flushState(AbstractTask.java:177) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamTask.flushState(StreamTask.java:582) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamTask.commit(StreamTask.java:536) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamTask.commit(StreamTask.java:524) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.AssignedTasks.commit(AssignedTasks.java:226) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.TaskManager.commitAll(TaskManager.java:529) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamThread.maybeCommit(StreamThread.java:959) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:813) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:698) [kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:671) [kafka-streams-2.4.0.jar:?]
Caused by: java.lang.ClassCastException: [B cannot be cast to java.lang.String
    at com.pan.pcs.dlp.kafkamerger.MergeObjectMetadataClassification$$anon$1.apply(MergeObjectMetadataClassification.scala:19) ~[classes/:?]
    at org.apache.kafka.streams.kstream.internals.KTableKTableInnerJoin$KTableKTableJoinProcessor.process(KTableKTableInnerJoin.java:110) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.kstream.internals.KTableKTableInnerJoin$KTableKTableJoinProcessor.process(KTableKTableInnerJoin.java:67) ~[kafka-streams-2.4.0.jar:?]
    at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:118) ~[kafka-streams-2.4.0.jar:?]
    ... 24 more

---

默认情况下，将使用

ByteArraySeOrders

，如果

LongSerde

用于键，而

StringSerde

用于值，则错误消息表明您的程序仍然使用它们

如果您使用官方的Scala API并加载相应的显式代码，那么应该自动使用正确的SERDE。否则，您可能需要通过

StreamsConfig

设置不同的默认serdes，通过将

consumered.with（…）

传递到

表（…）

操作符中，在每个操作符的基础上覆盖它们

---

查看文档了解详细信息：

默认情况下使用

ByteArraySeOrders

，错误消息表明，如果

LongSerde

用于键，而

StringSerde

用于值，则您的程序仍然使用它们

如果您使用官方的Scala API并加载相应的显式代码，那么应该自动使用正确的SERDE。否则，您可能需要通过

StreamsConfig

设置不同的默认serdes，通过将

consumered.with（…）

传递到

表（…）

操作符中，在每个操作符的基础上覆盖它们

有关详细信息，请查看文档：