Andy Bryant created KAFKA-6378:
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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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