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https://issues.apache.org/jira/browse/HDFS-10220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15281637#comment-15281637
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Daryn Sharp commented on HDFS-10220:
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IMHO lease recovery is not critical enough to warrant an impact on throughput.
The callq on large busy clusters (ex. ~30k ops/sec) will easily fill or
overflow. I'd rather see it be more on the order of single-digit ms. At the
end of cycle, if it broke out early then perhaps it could sleep for less than
2s.
> A large number of expired leases can make namenode unresponsive and cause
> failover
> ----------------------------------------------------------------------------------
>
> 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,
> HADOOP-10220.006.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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