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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-142) In 0.20, move blocks being written into a blocksBeingWritten directory
Date Thu, 06 May 2010 03:35:50 GMT

    [ https://issues.apache.org/jira/browse/HDFS-142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12864636#action_12864636
] 

Todd Lipcon commented on HDFS-142:
----------------------------------

It's accessed from multiple threads, but those threads are always synchronized on the FSNamesystem
lock anyway - none of the lease-related stuff has any actual concurrency. Marking it volatile
wouldn't cause any harm, but I think we assume pretty much everywhere that the leases aren't
mucked with without holding the coarse grain lock.

BTW, on an unrelated note, I found that TestNodeCount times out due to the MiniDFSCluster
changes imported by HDFS-409 - will upload a fix for that here soon.

> In 0.20, move blocks being written into a blocksBeingWritten directory
> ----------------------------------------------------------------------
>
>                 Key: HDFS-142
>                 URL: https://issues.apache.org/jira/browse/HDFS-142
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Raghu Angadi
>            Assignee: dhruba borthakur
>            Priority: Blocker
>         Attachments: appendQuestions.txt, deleteTmp.patch, deleteTmp2.patch, deleteTmp5_20.txt,
deleteTmp5_20.txt, deleteTmp_0.18.patch, handleTmp1.patch, hdfs-142-commitBlockSynchronization-unknown-datanode.txt,
HDFS-142-deaddn-fix.patch, HDFS-142-finalize-fix.txt, hdfs-142-minidfs-fix-from-409.txt, HDFS-142-multiple-blocks-datanode-exception.patch,
hdfs-142-recovery-reassignment-and-bbw-cleanup.txt, hdfs-142-testcases.txt, hdfs-142-testleaserecovery-fix.txt,
HDFS-142_20.patch, testfileappend4-deaddn.txt
>
>
> Before 0.18, when Datanode restarts, it deletes files under data-dir/tmp  directory since
these files are not valid anymore. But in 0.18 it moves these files to normal directory incorrectly
making them valid blocks. One of the following would work :
> - remove the tmp files during upgrade, or
> - if the files under /tmp are in pre-18 format (i.e. no generation), delete them.
> Currently effect of this bug is that, these files end up failing block verification and
eventually get deleted. But cause incorrect over-replication at the namenode before that.
> Also it looks like our policy regd treating files under tmp needs to be defined better.
Right now there are probably one or two more bugs with it. Dhruba, please file them if you
rememeber.

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