Kirk True created KAFKA-16556:
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Summary: 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
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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