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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6527) Edit log corruption due to defered INode removal
Date Mon, 16 Jun 2014 00:43:02 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14032066#comment-14032066
] 

Jing Zhao commented on HDFS-6527:
---------------------------------

Besides, is it possible that we can hide the sleepForTesting part inside a customized BlockPlacementPolicy?
The customized BlockPlacementPolicy implementation uses the same policy as BlockPlacementPolicyDefault,
but make the thread sleep 1s before returning. In this way we do not need to inject testing
code into FSNamesystem.

> Edit log corruption due to defered INode removal
> ------------------------------------------------
>
>                 Key: HDFS-6527
>                 URL: https://issues.apache.org/jira/browse/HDFS-6527
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.4.0
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>            Priority: Blocker
>         Attachments: HDFS-6527.branch-2.4.patch, HDFS-6527.trunk.patch, HDFS-6527.v2.patch,
HDFS-6527.v3.patch
>
>
> We have seen a SBN crashing with the following error:
> {panel}
> \[Edit log tailer\] ERROR namenode.FSEditLogLoader:
> Encountered exception on operation AddBlockOp
> [path=/xxx,
> penultimateBlock=NULL, lastBlock=blk_111_111, RpcClientId=,
> RpcCallId=-2]
> java.io.FileNotFoundException: File does not exist: /xxx
> {panel}
> This was caused by the deferred removal of deleted inodes from the inode map. Since getAdditionalBlock()
acquires FSN read lock and then write lock, a deletion can happen in between. Because of deferred
inode removal outside FSN write lock, getAdditionalBlock() can get the deleted inode from
the inode map with FSN write lock held. This allow addition of a block to a deleted file.
> As a result, the edit log will contain OP_ADD, OP_DELETE, followed by
>  OP_ADD_BLOCK.  This cannot be replayed by NN, so NN doesn't start up or SBN crashes.



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