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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2184) Zookeeper Client should re-resolve hosts when connection attempts fail
Date Fri, 02 Feb 2018 14:32:00 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16350400#comment-16350400
] 

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

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

    https://github.com/apache/zookeeper/pull/451#discussion_r165658965
  
    --- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java ---
    @@ -57,29 +62,12 @@
          */
         public StaticHostProvider(Collection<InetSocketAddress> serverAddresses) {
             for (InetSocketAddress address : serverAddresses) {
    -            try {
    -                InetAddress ia = address.getAddress();
    -                InetAddress resolvedAddresses[] = InetAddress.getAllByName((ia != null)
? ia.getHostAddress() :
    -                        address.getHostName());
    -                for (InetAddress resolvedAddress : resolvedAddresses) {
    -                    // If hostName is null but the address is not, we can tell that
    -                    // the hostName is an literal IP address. Then we can set the host
string as the hostname
    -                    // safely to avoid reverse DNS lookup.
    -                    // As far as i know, the only way to check if the hostName is null
is use toString().
    -                    // Both the two implementations of InetAddress are final class, so
we can trust the return value of
    -                    // the toString() method.
    -                    if (resolvedAddress.toString().startsWith("/")
    -                            && resolvedAddress.getAddress() != null) {
    -                        this.serverAddresses.add(
    -                                new InetSocketAddress(InetAddress.getByAddress(
    -                                        address.getHostName(),
    -                                        resolvedAddress.getAddress()),
    -                                        address.getPort()));
    -                    } else {
    -                        this.serverAddresses.add(new InetSocketAddress(resolvedAddress.getHostAddress(),
address.getPort()));
    -                    }
    -                }
    -            } catch (UnknownHostException e) {
    +			try {
    --- End diff --
    
    Fixing.


> 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, 3.4.7, 3.4.8, 3.4.9, 3.4.10, 3.5.0, 3.5.1, 3.5.2, 3.5.3,
3.4.11
>         Environment: Ubuntu 14.04 host, Docker containers for Zookeeper & Kafka
>            Reporter: Robert P. Thille
>            Assignee: Flavio Junqueira
>            Priority: Blocker
>              Labels: easyfix, patch
>             Fix For: 3.5.4, 3.4.12
>
>         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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