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https://issues.apache.org/jira/browse/HDFS-10220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15262383#comment-15262383
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Ravi Prakash commented on HDFS-10220:
-------------------------------------

Is there a need to renew the lease? That would prevent it from being checked 
for another {{LEASE_HARDLIMIT_PERIOD}}. Could we simply change {{Lease 
leaseToCheck = sortedLeases.poll();}} to {{Lease leaseToCheck = 
sortedLeases.peek();}}? And add it to {{removing}} in case {{completed}} is 
true. I'd also propose to remove the {{removing.add(id);}} from the catch 
block. [~wheat9], [~jingzhao] you made these changes in HDFS-6757 . Do you have 
any comments?

> Namenode failover due to too long loking in LeaseManager.Monitor
> ----------------------------------------------------------------
>
>                 Key: HDFS-10220
>                 URL: https://issues.apache.org/jira/browse/HDFS-10220
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Nicolas Fraison
>            Assignee: Nicolas Fraison
>            Priority: Minor
>         Attachments: HADOOP-10220.001.patch, HADOOP-10220.002.patch, 
> HADOOP-10220.003.patch, HADOOP-10220.004.patch, HADOOP-10220.005.patch, 
> threaddump_zkfc.txt
>
>
> I have faced a namenode failover due to unresponsive namenode detected by the 
> zkfc with lot's of WARN messages (5 millions) like this one:
> _org.apache.hadoop.hdfs.StateChange: BLOCK* internalReleaseLease: All 
> existing blocks are COMPLETE, lease removed, file closed._
> On the threaddump taken by the zkfc there are lots of thread blocked due to a 
> lock.
> Looking at the code, there are a lock taken by the LeaseManager.Monitor when 
> some lease must be released. Due to the really big number of lease to be 
> released the namenode has taken too many times to release them blocking all 
> other tasks and making the zkfc thinking that the namenode was not 
> available/stuck.
> The idea of this patch is to limit the number of leased released each time we 
> check for lease so the lock won't be taken for a too long time period.



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