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https://issues.apache.org/jira/browse/HADOOP-17052?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mingliang Liu resolved HADOOP-17052.
------------------------------------
    Fix Version/s: 3.4.0
                   3.3.1
                   2.10.1
                   3.2.2
                   3.1.4
                   2.9.3
     Hadoop Flags: Reviewed
       Resolution: Fixed

Committed to all fixed versions branches. Thanks [~dhegde] for the reporting 
and providing a fix; thanks [~hemanthboyina] for review.

> NetUtils.connect() throws unchecked exception (UnresolvedAddressException) 
> causing clients to abort
> ---------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-17052
>                 URL: https://issues.apache.org/jira/browse/HADOOP-17052
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: hdfs-client
>    Affects Versions: 2.10.0, 2.9.2, 3.2.1, 3.1.3
>            Reporter: Dhiraj Hegde
>            Assignee: Dhiraj Hegde
>            Priority: Major
>             Fix For: 2.9.3, 3.1.4, 3.2.2, 2.10.1, 3.3.1, 3.4.0
>
>         Attachments: read_failure.log, write_failure1.log, write_failure2.log
>
>
> Hadoop components are increasingly being deployed on VMs and containers. One 
> aspect of this environment is that DNS is dynamic. Hostname records get 
> modified (or deleted/recreated) as a container in Kubernetes (or even VM) is 
> being created/recreated. In such dynamic environments, the initial DNS 
> resolution request might return resolution failure briefly as DNS client 
> doesn't always get the latest records. This has been observed in Kubernetes 
> in particular. In such cases NetUtils.connect() appears to throw 
> java.nio.channels.UnresolvedAddressException.  In much of Hadoop code (like 
> DFSInputStream and DFSOutputStream), the code is designed to retry 
> IOException. However, since UnresolvedAddressException is not child of 
> IOException, no retry happens and the code aborts immediately. It is much 
> better if NetUtils.connect() throws java.net.UnknownHostException as that is 
> derived from IOException and the code will treat this as a retry-able error.



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