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Date: Fri, 21 Jul 2017 05:56:02 +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 05:56:19 -0000


    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1669?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16095820#comment-16095820 ] 

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

Github user eribeiro commented on the issue:

    https://github.com/apache/zookeeper/pull/312
  
     @CheneySun Don't forget to replicate these changes on `NettyServerCnxn` and its factory. It's important to let them in sync as much as possible, even more if you are adding a new data structure to speed up this part of the code: https://github.com/apache/zookeeper/blob/master/src/java/main/org/apache/zookeeper/server/NettyServerCnxnFactory.java#L414-L423


> 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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