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https://issues.apache.org/jira/browse/KAFKA-16556?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kirk True reassigned KAFKA-16556:
---------------------------------
Assignee: Kirk True
> Race condition between ConsumerRebalanceListener and SubscriptionState
> ----------------------------------------------------------------------
>
> Key: KAFKA-16556
> URL: https://issues.apache.org/jira/browse/KAFKA-16556
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.7.0
> Reporter: Kirk True
> Assignee: Kirk True
> Priority: Blocker
> Labels: kip-848-client-support
> Fix For: 3.8.0
>
>
> There appears to be a race condition between invoking the
> {{ConsumerRebalanceListener}} callbacks on reconciliation and
> {{initWithCommittedOffsetsIfNeeded}} in the consumer.
>
> The membership manager adds the newly assigned partitions to the
> {{{}SubscriptionState{}}}, but marks them as
> {{{}pendingOnAssignedCallback{}}}. Then, after the
> {{ConsumerRebalanceListener.onPartitionsAssigned()}} completes, the
> membership manager will invoke {{enablePartitionsAwaitingCallback}} to set
> all of those partitions' 'pending' flag to false.
>
> During the main {{Consumer.poll()}} loop, {{AsyncKafkaConsumer}} may need to
> call {{initWithCommittedOffsetsIfNeeded()}} if the positions aren't already
> cached. Inside {{{}initWithCommittedOffsetsIfNeeded{}}}, the consumer calls
> the subscription's {{initializingPartitions}} method to get a set of the
> partitions for which to fetch their committed offsets. However,
> {{SubscriptionState.initializingPartitions()}} only returns partitions that
> have the {{pendingOnAssignedCallback}} flag set to to false.
>
> The result is: * If the {{MembershipManagerImpl.assignPartitions()}} future
> is completed on the background thread first, the 'pending' flag is set to
> false. On the application thread, when
> {{SubscriptionState.initializingPartitions()}} is called, it returns the
> partition, and we fetch its committed offsets
> * If instead the application thread calls
> {{SubscriptionState.initializingPartitions()}} first, the partitions's
> 'pending' flag is still set to false, and so the partition is omitted from
> the returned set. The {{updateFetchPositions()}} method then continues on and
> re-initializes the partition's fetch offset to 0.
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