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https://issues.apache.org/jira/browse/KAFKA-5879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dong Lin updated KAFKA-5879:
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Fix Version/s: 1.0.0
> Controller should read the latest IsrChangeNotification znodes when handling
> IsrChangeNotification event
> --------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-5879
> URL: https://issues.apache.org/jira/browse/KAFKA-5879
> Project: Kafka
> Issue Type: Bug
> Reporter: Dong Lin
> Assignee: Dong Lin
> Priority: Critical
> Fix For: 1.0.0
>
>
> Currently controller can be very inefficient in handling
> IsrChangeNotification event because it may need to access znode O(n^2) times
> to handle O( n ) IsrChangeNotification znodes.
> For example, say there are 100 IsrChangeNotification nodes added to the
> zookeeper. This will generate 100 IsrChangeNotification events with children
> [1], [1, 2], [1, 2, 3], ... [1, 2, .. 100]. Let's say the controller now
> needs to handle the IsrChangeNotification event with children [1, 2, ...
> 100]. Controller will read zookeeper 100 times, delete these 100 znodes,
> which further generates 100 IsrChangeNotification events with children count
> from 0 to 99.
> The main cause of the problem is that, controller will attempt to access
> zookeeper n times, where n is the count of the children at the time the
> IsrChangeNotification event is generated, even though there is no
> IsrChangeNotification znodes in the zookeeper.
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