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Date: Fri, 21 Jul 2017 08:58:00 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ZOOKEEPER-1669) Operations to server will be
 timed-out while thousands of sessions expired same time
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archived-at: Fri, 21 Jul 2017 08:58:12 -0000


    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1669?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16095982#comment-16095982 ] 

ASF GitHub Bot commented on ZOOKEEPER-1669:
-------------------------------------------

Github user CheneySun commented on the issue:

    https://github.com/apache/zookeeper/pull/312
  
    @eribeiro Thanks for your reivew, I will replicate the changes to NettyServerCnxn. 
    
    BTW, how to make use of NettyServerCnxn as the underlying transport? The NIOServerCnxn is default transport implementation, and I didn't find the knobs to switch to use NettyServerCnxn.


> Operations to server will be timed-out while thousands of sessions expired same time
> ------------------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-1669
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1669
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: server
>    Affects Versions: 3.3.5
>            Reporter: tokoot
>            Assignee: Cheney Sun
>              Labels: performance
>
> If there are thousands of clients, and most of them disconnect with server same time(client restarted or servers partitioned with clients), the server will busy to close those "connections" and become unavailable. The problem is in following:
>   private void closeSessionWithoutWakeup(long sessionId) {
>       HashSet<NIOServerCnxn> cnxns;
>           synchronized (this.cnxns) {
>               cnxns = (HashSet<NIOServerCnxn>)this.cnxns.clone();  // other thread will block because of here
>           }
>       ...
>   }


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