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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-1142) Lease recovery doesn't reassign lease when triggered by append()
Date Fri, 21 May 2010 05:37:19 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12869878#action_12869878
] 

dhruba borthakur commented on HDFS-1142:
----------------------------------------

Let me understand this one. Suppose a client A has a write-lease on a file. It is doing some
write/sync to this file. Then another client B decides to invoke append() to the same file.
If we have exceeded the soft-timeout limit, then the B's append call will trigger lease recovery.
However, at this point (when the lease recovery is starting), the lease is technically still
owned by A. A can continue to sync/write data to the file. If client B now successfully acquires
the lease, then from that moment onwards, any new sync/writes from A will start to fail. isn't
that behaviour enough to support HBase region recovery?


> Lease recovery doesn't reassign lease when triggered by append()
> ----------------------------------------------------------------
>
>                 Key: HDFS-1142
>                 URL: https://issues.apache.org/jira/browse/HDFS-1142
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.21.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hdfs-1142.txt, hdfs-1142.txt
>
>
> If a soft lease has expired and another writer calls append(), it triggers lease recovery
but doesn't reassign the lease to a new owner. Therefore, the old writer can continue to allocate
new blocks, try to steal back the lease, etc. This is for the testRecoveryOnBlockBoundary
case of HDFS-1139

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