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https://issues.apache.org/jira/browse/FLINK-11987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16833650#comment-16833650
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LIU Xiao commented on FLINK-11987:
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[~StephanEwen] We don't have much knowledge on this StateDescriptor so we
choose to fix kafka connector. Fixing StateDescriptor is indeed a better way.
Should I change my PR to fix StateDescriptor?
> Kafka producer occasionally throws NullpointerException
> -------------------------------------------------------
>
> Key: FLINK-11987
> URL: https://issues.apache.org/jira/browse/FLINK-11987
> Project: Flink
> Issue Type: Bug
> Components: Connectors / Kafka
> Affects Versions: 1.6.3, 1.6.4, 1.7.2
> Environment: Flink 1.6.2 (Standalone Cluster)
> Oracle JDK 1.8u151
> Centos 7.4
> Reporter: LIU Xiao
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 1.7.3, 1.6.5, 1.8.1
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> We are using Flink 1.6.2 in our production environment, and kafka producer
> occasionally throws NullpointerException.
> We found in line 175 of
> flink/flink-connectors/flink-connector-kafka-0.11/src/main/java/org/apache/flink/streaming/connectors/kafka/FlinkKafkaProducer011.java,
> NEXT_TRANSACTIONAL_ID_HINT_DESCRIPTOR was created as a static variable.
> Then in line 837,
> "context.getOperatorStateStore().getUnionListState(NEXT_TRANSACTIONAL_ID_HINT_DESCRIPTOR);"
> was called, and that leads to line 734 of
>
> flink/flink-runtime/src/main/java/org/apache/flink/runtime/state/DefaultOperatorStateBackend.java:
> "stateDescriptor.initializeSerializerUnlessSet(getExecutionConfig());"
> In function initializeSerializerUnlessSet(line 283 of
> flink/flink-core/src/main/java/org/apache/flink/api/common/state/StateDescriptor.java):
> if (serializer == null) {
> checkState(typeInfo != null, "no serializer and no type info");
> // instantiate the serializer
> serializer = typeInfo.createSerializer(executionConfig);
> // we can drop the type info now, no longer needed
> typeInfo = null;
> }
> "serializer = typeInfo.createSerializer(executionConfig);" is the line which
> throws the exception.
> We think that's because multiple subtasks of the same producer in a same
> TaskManager share a same NEXT_TRANSACTIONAL_ID_HINT_DESCRIPTOR.
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