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https://issues.apache.org/jira/browse/KAFKA-1503?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jianwen Wang updated KAFKA-1503:
--------------------------------

    Fix Version/s: 0.8.1.1
           Labels: patch  (was: )
           Status: Patch Available  (was: Open)

The first live broker in ISR was used as new leader. Since
 the order of liveBrokersInIsr list is not event distributed within live
 brokers, all partitions will be hosted on one broker as time goes on.

Now use the first live replica broker in ISR (liveAssignedReplicas filtered by 
liveBrokersInIsr) as the replica order is strictly evenly distributed.


> 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: 0.8.1.1, 0.8.0
>         Environment: 0.8.1.1 
>            Reporter: Jianwen Wang
>            Assignee: Neha Narkhede
>              Labels: patch
>             Fix For: 0.8.1.1
>
>
> 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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