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From "Kihwal Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6618) Remove deleted INodes from INodeMap right away
Date Wed, 09 Jul 2014 17:23:05 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14056477#comment-14056477
] 

Kihwal Lee commented on HDFS-6618:
----------------------------------

With the new patch {{removedINodes}} is passed to {{FSNamesystem#removePathAndBlocks()}} while
in the write lock. The method was modified to conditionally acquire the directory lock.  I
didn't move the removal to {{FSDirectory}}, since we may want to do something with the inodes
in {{FSNamesystem}} later as a part of failure handling in a separate jira.

> Remove deleted INodes from INodeMap right away
> ----------------------------------------------
>
>                 Key: HDFS-6618
>                 URL: https://issues.apache.org/jira/browse/HDFS-6618
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.5.0
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>            Priority: Blocker
>         Attachments: HDFS-6618.AbstractList.patch, HDFS-6618.inodeRemover.patch, HDFS-6618.inodeRemover.v2.patch,
HDFS-6618.patch, HDFS-6618.simpler.patch
>
>
> After HDFS-6527, we have not seen the edit log corruption for weeks on multiple clusters
until yesterday. Previously, we would see it within 30 minutes on a cluster.
> But the same condition was reproduced even with HDFS-6527.  The only explanation is that
the RPC handler thread serving {{addBlock()}} was accessing stale parent value.  Although
nulling out parent is done inside the {{FSNamesystem}} and {{FSDirectory}} write lock, there
is no memory barrier because there is no "synchronized" block involved in the process.
> I suggest making parent volatile.



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