[jira] [Commented] (HDFS-14651) DeadNodeDetector checks dead node periodically

["Ahmed Hussein (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-14651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17027943#comment-17027943 ] 

Ahmed Hussein commented on HDFS-14651:
--------------------------------------

Hi [~leosun08] and [~linyiqun]!
I am looking at the timeouts caused by the changes in this patch HDFS-15147

I have couple of questions:
# what is the usage of {{deadNodeDetectInterval}} ? As far as I understand, every call to {{checkDeadNodes()}} will change the state to {{IDLE}} forcing the {{DeadNodeDetector}} to sleep for {{IDLE_SLEEP_MS}}. So, why do we need {{deadNodeDetectInterval}} if the actual time gap between every check is {{IDLE_SLEEP_MS}}?
# Correct me if I am wrong: {{stopDeadNodeDetectorThread.stopDeadNodeDetectorThread()}} is supposed to stop the deadNodeDetector thread; but it looks like the implementation never of the runnable  never terminates. {{DeadNodeDetector}} surpresses all interrupts and never checks for a termination flag. Therefore, the caller will just hang for 3 seconds waiting to join. 

> DeadNodeDetector checks dead node periodically
> ----------------------------------------------
>
>                 Key: HDFS-14651
>                 URL: https://issues.apache.org/jira/browse/HDFS-14651
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Lisheng Sun
>            Assignee: Lisheng Sun
>            Priority: Major
>             Fix For: 3.3.0
>
>         Attachments: HDFS-14651.001.patch, HDFS-14651.002.patch, HDFS-14651.003.patch, HDFS-14651.004.patch, HDFS-14651.005.patch, HDFS-14651.006.patch, HDFS-14651.007.patch, HDFS-14651.008.patch
>
>
> DeadNodeDetector checks dead node periodically.
> DeadNodeDetector periodically detect the Node in DeadNodeDetector#deadnode, If the access is successful, the Node will be moved from DeadNodeDetector#deadnode. Continuous detection of the dead node is necessary. The DataNode need rejoin the cluster due to a service restart/machine repair. The DataNode may be permanently excluded if there is no added probe mechanism.



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