[jira] Commented: (HADOOP-5741) In Datanode, update block may fail due to length inconsistency

["dhruba borthakur (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-5741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12707769#action_12707769 ] 

dhruba borthakur commented on HADOOP-5741:
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The getBlockMetaDataInfo() should first terminate all open connections to the block and then return the size of the block. Then it is guaranteed that nobody can change the length of the block between the getBlockMetaDataInfo() and updateBlock() calls. This is documented in Step 5 in https://issues.apache.org/jira/browse/HADOOP-4663?focusedCommentId=12674490&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12674490

will this solve your problem?

> In Datanode, update block may fail due to length inconsistency
> --------------------------------------------------------------
>
>                 Key: HADOOP-5741
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5741
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>            Reporter: Tsz Wo (Nicholas), SZE
>
> When a primary datanode tries to recover a block.  It calls getBlockMetaDataInfo(..) to obtains information like block length from each datanode.  Then, it calls updateBlock(..).
> The block length returned in getBlockMetaDataInfo(..) may be obtained from a unclosed local block file F.   However, in updateBlock(..), it first closes F (if F is open) and then gets the length.  These two lengths may be different.  In such case, updateBlock(..) throws an exception.

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