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  1. Kafka
  2. KAFKA-6378

NullPointerException on KStream-GlobalKTable leftJoin when KeyValueMapper returns null

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Details

    • Bug
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • 1.0.0
    • 1.0.1, 1.1.0, 2.0.0
    • streams
    • None

    Description

      On a Stream->GlobalKTable leftJoin if the KeyValueMapper returns null, the stream fails with a NullPointerException (see stacktrace below). On Kafka 0.11.0.0 the stream processes this successfully, calling the ValueJoiner with the table value set to null.

      The use-case for this is joining a stream to a table containing reference data where the stream foreign key may be null. There is no straight-forward workaround in this case with Kafka 1.0.0 without having to resort to either generating a key that will never match or branching the stream for records that don't have the foreign key.

      Exception in thread "workshop-simple-example-client-StreamThread-1" java.lang.NullPointerException
      at java.base/java.util.Objects.requireNonNull(Objects.java:221)
      at org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:136)
      at org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:35)
      at org.apache.kafka.streams.state.internals.InnerMeteredKeyValueStore.get(InnerMeteredKeyValueStore.java:184)
      at org.apache.kafka.streams.state.internals.MeteredKeyValueBytesStore.get(MeteredKeyValueBytesStore.java:116)
      at org.apache.kafka.streams.kstream.internals.KTableSourceValueGetterSupplier$KTableSourceValueGetter.get(KTableSourceValueGetterSupplier.java:49)
      at org.apache.kafka.streams.kstream.internals.KStreamKTableJoinProcessor.process(KStreamKTableJoinProcessor.java:56)
      at org.apache.kafka.streams.processor.internals.ProcessorNode$1.run(ProcessorNode.java:46)
      at org.apache.kafka.streams.processor.internals.StreamsMetricsImpl.measureLatencyNs(StreamsMetricsImpl.java:208)
      at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:124)
      at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:85)
      at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:80)
      at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:216)
      at org.apache.kafka.streams.processor.internals.AssignedTasks.process(AssignedTasks.java:403)
      at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:317)
      at org.apache.kafka.streams.processor.internals.StreamThread.processAndMaybeCommit(StreamThread.java:942)
      at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:822)
      at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:774)
      at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:744)

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            kiwiandy Andy Bryant
            kiwiandy Andy Bryant
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              Created:
              Updated:
              Resolved: