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https://issues.apache.org/jira/browse/HDFS-9422?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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He Liangliang updated HDFS-9422:
--------------------------------
    Description: In DirectoryScanner, the scan call hold the global dataset 
lock for quite long time (typically max value > 5 secs for 500k blocks). This 
will stuck the client which need acquire this lock. For applications like 
HBase, this will affect the latency. In fact, this lock is unnecessary.  (was: 
In DirectoryScanner, the scan call hold the global dataset lock for quite long 
time (typically > 5 secs for 500k blocks). This will stuck the client which 
need acquire this lock. For applications like HBase, this will affect the 
latency. In fact, this lock is unnecessary.)

> Unnecessary FsDatasetImpl locking in DirectoryScanner cause periodic datanode 
> pauses
> ------------------------------------------------------------------------------------
>
>                 Key: HDFS-9422
>                 URL: https://issues.apache.org/jira/browse/HDFS-9422
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: He Liangliang
>            Assignee: He Liangliang
>         Attachments: HDFS-9422.patch
>
>
> In DirectoryScanner, the scan call hold the global dataset lock for quite 
> long time (typically max value > 5 secs for 500k blocks). This will stuck the 
> client which need acquire this lock. For applications like HBase, this will 
> affect the latency. In fact, this lock is unnecessary.



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