guwensheng created KAFKA-20312:
----------------------------------
Summary: KafkaConsumer poll may happens NullPointerException
Key: KAFKA-20312
URL: https://issues.apache.org/jira/browse/KAFKA-20312
Project: Kafka
Issue Type: Bug
Components: clients
Affects Versions: 3.9.1
Reporter: guwensheng
Fix For: 4.1.0, 4.0.0, 3.9.0
jdk:21
KafkaClient： 3.9.1
When I use KafkaConsumer poll to pull messages from Kafka, there is a low
probability that I encounter a null pointer issue.
I thought about it, and this might be because some partitions do not have a
leader when the Kafka service encounters an exception.
The problem stack is as follows:
```
Caused by: java.lang.NullPointerException: element cannot be mapped to a null
key
at java.base/java.util.Objects.requireNonNull(Unknown Source) ~[?:?]
at java.base/java.util.stream.Collectors.lambda$groupingBy$53(Unknown
Source) ~[?:?]
at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(Unknown
Source) ~[?:?]
at
java.base/java.util.HashMap$EntrySpliterator.forEachRemaining(Unknown Source)
~[?:?]
at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source)
~[?:?]
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown
Source) ~[?:?]
at
java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(Unknown
Source) ~[?:?]
at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source)
~[?:?]
at java.base/java.util.stream.ReferencePipeline.collect(Unknown Source)
~[?:?]
at
org.apache.kafka.clients.consumer.internals.OffsetFetcherUtils.regroupPartitionMapByNode(OffsetFetcherUtils.java:187)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.OffsetFetcher.groupListOffsetRequests(OffsetFetcher.java:379)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.OffsetFetcher.resetPositionsAsync(OffsetFetcher.java:214)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.OffsetFetcher.resetPositionsIfNeeded(OffsetFetcher.java:109)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.ClassicKafkaConsumer.updateFetchPositions(ClassicKafkaConsumer.java:1258)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.ClassicKafkaConsumer.updateAssignmentMetadataIfNeeded(ClassicKafkaConsumer.java:708)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.ClassicKafkaConsumer.poll(ClassicKafkaConsumer.java:663)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.internals.ClassicKafkaConsumer.poll(ClassicKafkaConsumer.java:643)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:878)
~[kafka-clients-3.9.0-htrunk7.gdd.pub.r1.jar:?]
at
org.apache.kafka.streams.processor.internals.StreamThread.pollRequests(StreamThread.java:1347)
~[kafka-streams-3.9.0-htrunk6.gdd.pub.r1.jar:?]
at
org.apache.kafka.streams.processor.internals.StreamThread.pollPhase(StreamThread.java:1295)
~[kafka-streams-3.9.0-htrunk6.gdd.pub.r1.jar:?]
at
org.apache.kafka.streams.processor.internals.StreamThread.runOnceWithoutProcessingThreads(StreamThread.java:1028)
~[kafka-streams-3.9.0-htrunk6.gdd.pub.r1.jar:?]
at
org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:777)
~[kafka-streams-3.9.0-htrunk6.gdd.pub.r1.jar:?]
```
I understand that this is the cause of the null pointer issue, and I hope that
null pointer protection can be implemented here.
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