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From "Vishal Khandelwal (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2447) Zookeeper adds good delay when one of the quorum host is not reachable
Date Fri, 01 Jul 2016 10:25:11 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2447?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15358757#comment-15358757
] 

Vishal Khandelwal commented on ZOOKEEPER-2447:
----------------------------------------------

[~eribeiro] : did you tey this solution when a host is valid but it is shutdown. because in
method "ClientCnxnSocketNIO.registerAndConnect" makes a call to SocketChannel.connect and
it always passes whether the host is reachable or not. If it would have worked then we did
not have to wait for host timeout incase shutdown hsot scenario.

> 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: Vishal Khandelwal
>             Fix For: 3.5.3, 3.6.0
>
>         Attachments: 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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