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https://issues.apache.org/jira/browse/ZOOKEEPER-856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12903617#action_12903617
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Patrick Hunt commented on ZOOKEEPER-856:
----------------------------------------

Agree, this has been an issue we've discussed before (connection balancing) and 
should address. The most pronounced is when you restart a server - all the 
connections shift to the other servers and the restarted server has 0 
connections... 

> Connection imbalance leads to overloaded ZK instances
> -----------------------------------------------------
>
>                 Key: ZOOKEEPER-856
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-856
>             Project: Zookeeper
>          Issue Type: Bug
>            Reporter: Travis Crawford
>             Fix For: 3.4.0
>
>         Attachments: zk_open_file_descriptor_count_members.gif, 
> zk_open_file_descriptor_count_total.gif
>
>
> We've experienced a number of issues lately where "ruok" requests would take 
> upwards of 10 seconds to return, and ZooKeeper instances were extremely 
> sluggish. The sluggish instance requires a restart to make it responsive 
> again.
> I believe the issue is connections are very imbalanced, leading to certain 
> instances having many thousands of connections, while other instances are 
> largely idle.
> A potential solution is periodically disconnecting/reconnecting to balance 
> connections over time; this seems fine because sessions should not be 
> affected, and therefore ephemaral nodes and watches should not be affected.

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