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From "Hairong Kuang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5134) FSNamesystem#commitBlockSynchronization adds under-construction block locations to blocksMap
Date Fri, 13 Feb 2009 19:34:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5134?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12673361#action_12673361
] 

Hairong Kuang commented on HADOOP-5134:
---------------------------------------

After much thought, I'd like to +1 on the approach in this patch as an emergency fix to 0.18
and 0.19, but leaving the discussion of lease close semantics and block length inconsistency
handling to a later time.

Comments to the patch:
 lines 1897-1900 in the merged FSNamestem.java: why descriptors is not declared in the else
block. It seems that descriptors is used only there.
 line 1915: no need to initiate descriptors again
 line 1916: not sure if ">=" is needed. trunk uses only ">".

Could you please also upload a patch for 0.18?

> FSNamesystem#commitBlockSynchronization adds under-construction block locations to blocksMap
> --------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-5134
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5134
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.18.2
>            Reporter: Hairong Kuang
>            Assignee: dhruba borthakur
>            Priority: Blocker
>             Fix For: 0.18.4, 0.19.1
>
>         Attachments: commitBlockSync.patch
>
>
> From my understanding of sync/append design, an under construction block should not have
any block locations associated with it in the blocksMap. So an under construction block will
not be managed by ReplicationMonitor.
> However, if there is an error in the write pipeline, a lease recovery will trigger a
call, commitBlockSynchronization, to NN. This call will add the successfully-recovered datanodes
to blocksMap. This seems to violate the design. It should update the targets of the last block
at INode instead. 

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