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https://issues.apache.org/jira/browse/HDFS-15661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17265745#comment-17265745
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Wei-Chiu Chuang commented on HDFS-15661:
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I'm not familiar with the dead node detector -- it's a new feature.

The patch itself looks good. If the goal is to ensure that closing one dfs 
client doesn't prematurely terminate the deadnode detector thread, maybe a 
simpler approach is to use the CloseableReferenceCount class (in hadoop-common) 
to keep the reference count.

It seems like a good idea to keep a single dead node detector object. If I 
understand it correctly, the original design works in federated cluster. After 
this patch, the dead node information won't be shared between difference block 
pools.

> The DeadNodeDetector shouldn't be shared by different DFSClients.
> -----------------------------------------------------------------
>
>                 Key: HDFS-15661
>                 URL: https://issues.apache.org/jira/browse/HDFS-15661
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Jinglun
>            Assignee: Jinglun
>            Priority: Major
>         Attachments: HDFS-15661.001.patch
>
>
> Currently the DeadNodeDetector is a member of ClientContext. That means it is 
> shared by many different DFSClients. When one DFSClient.close() is invoked, 
> the DeadNodeDetecotor thread would be interrupted and impact other DFSClients.
> From the original design of HDFS-13571 we could see the DeadNodeDetector is 
> supposed to share dead nodes of many input streams from the same client. 
> We should move the DeadNodeDetector as a member of DFSClient instead of 
> ClientContext. 



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