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