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Date: Sat, 14 Jan 2017 22:35:26 +0000 (UTC)
From: "ASF GitHub Bot (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ZOOKEEPER-2184) Zookeeper Client should
 re-resolve hosts when connection attempts fail
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archived-at: Sat, 14 Jan 2017 22:35:31 -0000


    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15822976#comment-15822976 ] 

ASF GitHub Bot commented on ZOOKEEPER-2184:
-------------------------------------------

Github user fpj commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/150#discussion_r96125997
  
    --- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java ---
    @@ -45,6 +45,9 @@
     
         private int currentIndex = -1;
     
    +    // Don't re-resolve on first next() call
    +    private boolean connectedSinceNext = true;
    --- End diff --
    
    All calls to `next` and `onConnected` are from the `sendThread`. I don't see a reason for making volatile, unless we are doing it defensively. Let me know if I'm missing anything.
    
    Note that this pull request is for the 3.4 branch, we need a different patch for 3.5 and master.


> Zookeeper Client should re-resolve hosts when connection attempts fail
> ----------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-2184
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2184
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: java client
>    Affects Versions: 3.4.6, 3.5.0
>         Environment: Ubuntu 14.04 host, Docker containers for Zookeeper & Kafka
>            Reporter: Robert P. Thille
>            Assignee: Robert P. Thille
>              Labels: easyfix, patch
>             Fix For: 3.4.10, 3.5.3
>
>         Attachments: ZOOKEEPER-2184.patch
>
>
> Testing in a Docker environment with a single Kafka instance using a single Zookeeper instance. Restarting the Zookeeper container will cause it to receive a new IP address. Kafka will never be able to reconnect to Zookeeper and will hang indefinitely. Updating DNS or /etc/hosts with the new IP address will not help the client to reconnect as the zookeeper/client/StaticHostProvider resolves the connection string hosts at creation time and never re-resolves.
> A solution would be for the client to notice that connection attempts fail and attempt to re-resolve the hostnames in the connectString.


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