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https://issues.apache.org/jira/browse/KAFKA-1503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14039487#comment-14039487
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Jianwen Wang commented on KAFKA-1503:
-------------------------------------
Hi Guozhang,
The fully working auto rebalance will surely break that imbalance loop. But
I like to have a fix to make sure the leader is evenly distributed within live
brokers between two rebalances after one broker is down. As you can see, if the
auto rebalance interval is set to 5 minutes, the imbalance case (all partitions
on one broker) will stay for <= 5 minutes.
The fix I provided is to solve that particular case.
Thanks.
-jianwen
> all partitions are using same broker as their leader after broker is down
> -------------------------------------------------------------------------
>
> Key: KAFKA-1503
> URL: https://issues.apache.org/jira/browse/KAFKA-1503
> Project: Kafka
> Issue Type: Bug
> Components: controller
> Affects Versions: 0.8.0, 0.8.1.1
> Environment: 0.8.1.1
> Reporter: Jianwen Wang
> Assignee: Neha Narkhede
>
> The current leader selection always pick the first live broker in ISR when
> the current leader broker is down. Since the list of liveBrokerInIsr is not
> evenly distributed. As time goes on, all the partitions will use only one
> broker as its leader.
> I figured out a fix which is to use the first live broker in replica list
> which is also in ISR list. Since the liveAssignedReplicas is evenly
> distributed across brokers, all the partitions will be evenly distributed in
> the live brokers in ISR.
> The fix is:
> kafka-0.8.1.1-src/core/src/main/scala/kafka/controller/PartitionLeaderSelector.scala
> 71 71
> case false =>
> 72
> - val newLeader = liveBrokersInIsr.head
> 72
> + val liveReplicasInIsr = liveAssignedReplicas.filter(r =>
> liveBrokersInIsr.contains(r))
> 73
> + val newLeader = liveReplicasInIsr.head
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