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From "Nicolas Fraison (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-10220) Namenode failover due to too long loking in LeaseManager.Monitor
Date Thu, 21 Apr 2016 16:45:25 GMT

    [ https://issues.apache.org/jira/browse/HDFS-10220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15252179#comment-15252179
] 

Nicolas Fraison commented on HDFS-10220:
----------------------------------------

[~walter.k.su]
1. I think that it simplify the code
2. Ok I will removed this change as we only called it once since it is removed from loop lease
break
3. Ok I will change it to DEBUG
4. Counting the time since better in term of funcionnality but I'm afraid about adding extra
computation time on this check compare to a simple count of files. The idea is not to spend
more times to release those lease. What is your feeling about it?
5. It should solve the failover issue but it will let the lock being held during this release
of lease, slowing donw/stucking operation on the namenode

> 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, 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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