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From "Konstantin Shvachko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1707) Remove the DFS Client disk-based cache
Date Thu, 29 Nov 2007 22:05:43 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12546917
] 

Konstantin Shvachko commented on HADOOP-1707:
---------------------------------------------

Since you have just encountered that.
The same problem will potentially be in the following 3 methods
- nextBlockOutputStream()
- locateFollowingBlock()
- DFSOutputStream.close()

where the client sleeps under a lock. In general a thread should wait() instead of sleep()
under a lock.

> Remove the DFS Client disk-based cache
> --------------------------------------
>
>                 Key: HADOOP-1707
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1707
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: dfs
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>             Fix For: 0.16.0
>
>         Attachments: clientDiskBuffer.patch, clientDiskBuffer2.patch, clientDiskBuffer6.patch,
clientDiskBuffer7.patch, clientDiskBuffer8.patch, DataTransferProtocol.doc, DataTransferProtocol.html
>
>
> The DFS client currently uses a staging file on local disk to cache all user-writes to
a file. When the staging file accumulates 1 block worth of data, its contents are flushed
to a HDFS datanode. These operations occur sequentially.
> A simple optimization of allowing the user to write to another staging file while simultaneously
uploading the contents of the first staging file to HDFS will improve file-upload performance.

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