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https://issues.apache.org/jira/browse/HDFS-9143?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Walter Su resolved HDFS-9143.
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    Resolution: Duplicate

> updateCountForQuota method during EditlogTailer loadEdit can make SNN timeout 
> very often 
> -----------------------------------------------------------------------------------------
>
>                 Key: HDFS-9143
>                 URL: https://issues.apache.org/jira/browse/HDFS-9143
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.4.0, 2.6.0
>            Reporter: jiangyu
>            Priority: Minor
>
> I have seen many logs from datanodes in our cluster reporting socket timeout 
> when sending heartbeat or blockReceivedAndDeleted to Standby NameNode, but it 
> never happen to Active NameNode.  
> At first, i thought it maybe caused by Editlog Tailer fetch Editlog too much 
> making full gc, but after i watched the gc log, it is not. So i investigate 
> the code path and log, find it only take very few seconds for the SNN to 
> fetch the journal and merge it. But when you open the webpage of SNN during 
> merge processing, it can not response  like stop the world time of full GC, 
> but there is no gc at that time. So i jstack SNN for some time, and finding 
> all the time consumed by updateCountForQuota method in FSImage.  
> The updateCountForQuota is called ervry time when loadEdits, it update the 
> count of each directory with quota in the namespace from ROOT, besides it 
> hold the write lock of FSImage, so every time when SNN merge the edit from 
> JN, it is always making the stop world.  
> I don't think it is necessary for SNN to updateCountForQuota everytime when 
> tail the edit, when trasition to Active, it call updateCountForQuota and 
> never missing any quota data.



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