Swapnil Ghike created KAFKA-1096:
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Summary: An old controller coming out of long GC could update its
epoch to the latest controller's epoch
Key: KAFKA-1096
URL: https://issues.apache.org/jira/browse/KAFKA-1096
Project: Kafka
Issue Type: Bug
Affects Versions: 0.8
Reporter: Swapnil Ghike
If a controller GCs for too long, we could have two controllers in the cluster.
The controller epoch is supposed to minimize the damage in such a situation, as
the brokers will reject the requests sent by the controller with an older epoch.
When the old controller is still in long GC, a new controller could be elected.
This will fire ControllerEpochListener on the old controller. When it comes out
of GC, its ControllerEpochListener will update its own epoch to the new
controller's epoch. So both controllers are now able to send out requests with
the same controller epoch until the old controller's handleNewSession() can
execute in the controller lock.
ControllerEpochListener does not seem necessary, so we can probably delete it.
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