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Date: Wed, 3 Aug 2016 17:12:20 +0000 (UTC)
From: "Dan Benediktson (JIRA)" <jira@apache.org>
To: dev@zookeeper.apache.org
Message-ID: <JIRA.12979354.1465995386000.214061.1470244340529@Atlassian.JIRA>
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Subject: [jira] [Commented] (ZOOKEEPER-2447) Zookeeper adds  good delay when
 one of the quorum host is not reachable
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archived-at: Wed, 03 Aug 2016 17:12:27 -0000


    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15406240#comment-15406240 ] 

Dan Benediktson commented on ZOOKEEPER-2447:
--------------------------------------------

Correct, I don't think there is a patch in a completed state.

The patch I provided was just to avoid a specific problem during the most recent proposed solution: the problem where you try to connect using only a slice of the connection time, but the chosen slice is too small to reasonably expect a connection to succeed. I think [~eribeiro] offered to look at a comprehensive solution, so I'm assigning over to him for the time being.

> Zookeeper adds  good delay when one of the quorum host is not reachable
> -----------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-2447
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2447
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.4.6, 3.5.0
>            Reporter: Vishal Khandelwal
>            Assignee: Dan Benediktson
>             Fix For: 3.5.3, 3.6.0
>
>         Attachments: ZOOKEEPER-2447-MinConnectTimeoutOnly.patch, ZOOKEEPER-2447.3.5.patch, withfix.txt, withoutFix.txt
>
>
> StaticHostProvider --> resolveAndShuffle method adds all of the address which are valid in the quorum to the list, shuffles them and sends back to client connection class. If after shuffling if first node appear to be the one which is not reachable, Clientcnx.SendThread.run will keep on connecting to the failure till a timeout and the moves to a different node. This adds up random delay in zookeeper connection in case a host is down. Rather we could check if host is reachable in StaticHostProvider and ignore isReachable is false. Same as we do for UnknownHostException Exception.
> This can tested using following test code by providing a valid host which is not reachable. for quick test comment Collections.shuffle(tmpList, sourceOfRandomness); in StaticHostProvider.resolveAndShuffle
> {code}
>  @Test
>   public void test() throws Exception {
>     EventsWatcher watcher = new EventsWatcher();
>     QuorumUtil qu = new QuorumUtil(1);
>     qu.startAll();
>     
>     ZooKeeper zk =
>         new ZooKeeper("<hostnamet:2181," + qu.getConnString(), 180 * 1000, watcher);
>     
>     watcher.waitForConnected(CONNECTION_TIMEOUT * 5);
>     Assert.assertTrue("connection Established", watcher.isConnected());
>     zk.close();    
>   }
> {code}
> Following fix can be added to StaticHostProvider.resolveAndShuffle
> {code}
>  if(taddr.isReachable(4000 // can be some value)) {
>                       tmpList.add(new InetSocketAddress(taddr, address.getPort()));
>                     } 
> {code}


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