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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-1142) Lease recovery doesn't reassign lease when triggered by append()
Date Sat, 15 May 2010 00:09:42 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12867750#action_12867750

Todd Lipcon commented on HDFS-1142:

Hi Konstantin. Thanks for the detailed response.

bq. Suppose there is only one new client, and the old owner had died already. The client tries
create(). This triggers lease recovery on NN, which starts the recovery under HDFS_NameNode,
and throws RecoveryInProgressException back to the client. The client retries as expected,
and the next time gets AlreadyBeingCreatedException. Thinking that somebody else got lucky
before him the client bails out, which is not right as there is nobody esle competing for
the file. 

What if we specifically compare the holder to the HDFS_Namenode special value, and in this
case throw RecoveryInProgressException instead of AlreadyBeingCreatedException?

bq. Does that makes sense? I don't see a problem here. Do you have failing tests because of

Yes - please see the new test case included in the patch above. The issue is that the client
can continue to do things like completeFile or allocate new blocks while recovery is underway.

bq. For future reference it is very undesirable to declare public methods in FSNamesystem
to provide access to them from tests

I agree. However, in order to do mockito spying on commitBlockSynchronization, using a trampoline
class like NameNodeAdapter would not work. If you agree with my above points, I can see if
I can move the spy call into NameNodeAdapter itself.
BTW, isn't this the point of the "Private" InterfaceAudience annotation?

Let me know if you agree with the above idea (throwing RecoveryInProgressException when the
lease is held by HDFS_NameNode).

> 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
>            Priority: Blocker
>         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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