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https://issues.apache.org/jira/browse/KAFKA-708?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Neha Narkhede updated KAFKA-708:
--------------------------------
Attachment: kafka-708-v1.patch
Changes in this patch include -
1. Allowing the isr list to be empty. This can happen if all the brokers in the
isr fall out which can happen if all the replicas that host the partition are
down. In other words, the partition is offline. The problem was that if the
controller moves when the isr is empty or you restart the entire cluster, it
relied on a non-empty isr.
2. Marking the partition offline by setting the leader to -1 in zookeeper. This
is because, today there is no way for an external tool to figure out the list
of all offline partitions. If we were to build a Kafka cluster dashboard and
list partitions and their metadata, we would want to know the leader for each
partition. Until a new leader is elected, we continue to store the previous
leader in zookeeper. If the partition goes offline and no new leader will ever
come up, we still store the previous leader. This is not ideal and it might be
worth to store some value like -1 to denote an offline partition
3. Cleaned up logging for a partition. There were several places in the code
that used a custom string like "[%s, %d]" or "(%s, %d)" to print a partition.
This makes it very hard to trace the state changes on a partition while
troubleshooting. I changed everything in kafka.controller to standardize on the
toString() API of TopicAndPartition. I'm assuming the rest of the code will get
cleaned up as part of KAFKA-649
> ISR becomes empty while marking a partition offline
> ---------------------------------------------------
>
> Key: KAFKA-708
> URL: https://issues.apache.org/jira/browse/KAFKA-708
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.8, 0.8.1
> Reporter: Swapnil Ghike
> Assignee: Neha Narkhede
> Priority: Blocker
> Labels: bugs
> Fix For: 0.8
>
> Attachments: kafka-708-v1.patch, kafka-request.log.2013-01-16-15
>
>
> Attached state change log shows that ISR becomes empty when a partition is
> being marked as offline.
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