Jason Gustafson created KAFKA-13173:
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Summary: KRaft controller does not handle simultaneous broker
expirations correctly
Key: KAFKA-13173
URL: https://issues.apache.org/jira/browse/KAFKA-13173
Project: Kafka
Issue Type: Bug
Reporter: Jason Gustafson
In `ReplicationControlManager.fenceStaleBrokers`, we find all of the current
stale replicas and attempt to remove them from the ISR. However, when multiple
expirations occur at once, we do not properly accumulate the ISR changes. For
example, I ran a test where the ISR of a partition was initialized to [1, 2,
3]. Then I triggered a timeout of replicas 2 and 3 at the same time. The
records that were generated by `fenceStaleBrokers` were the following:
{code}
ApiMessageAndVersion(PartitionChangeRecord(partitionId=0,
topicId=_seg8hBuSymBHUQ1sMKr2g, isr=[1, 3], leader=1, replicas=null,
removingReplicas=null, addingReplicas=null) at version 0),
ApiMessageAndVersion(FenceBrokerRecord(id=2, epoch=102) at version 0),
ApiMessageAndVersion(PartitionChangeRecord(partitionId=0,
topicId=_seg8hBuSymBHUQ1sMKr2g, isr=[1, 2], leader=1, replicas=null,
removingReplicas=null, addingReplicas=null) at version 0),
ApiMessageAndVersion(FenceBrokerRecord(id=3, epoch=103) at version 0)]
{code}
First the ISR is shrunk to [1, 3] as broker 2 is fenced. We also see the record
to fence broker 2. Then the ISR is modified to [1, 2] as the fencing of broker
3 is handled. So we did not account for the fact that we had already fenced
broker 2 in the request.
A simple solution for now is to change the logic to handle fencing only one
broker at a time.
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