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From "Andy Bryant (JIRA)" <j...@apache.org>
Subject [jira] [Created] (KAFKA-6378) NullPointerException on KStream-GlobalKTable leftJoin when KeyValueMapper returns null
Date Mon, 18 Dec 2017 02:44:00 GMT
Andy Bryant created KAFKA-6378:
----------------------------------

             Summary: NullPointerException on KStream-GlobalKTable leftJoin when KeyValueMapper
returns null
                 Key: KAFKA-6378
                 URL: https://issues.apache.org/jira/browse/KAFKA-6378
             Project: Kafka
          Issue Type: Bug
          Components: streams
    Affects Versions: 1.0.0
            Reporter: Andy Bryant


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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