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https://issues.apache.org/jira/browse/HDFS-570?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HDFS-570:
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Description:
In order to support read consistency, DFSClient needs the file length at the
file opening time. In the current implmentation, DFSClient obtains the file
length at the file opening time but the length is inaccurate if the file is
being written.
For more details, see Section 4 in the [append design
doc|https://issues.apache.org/jira/secure/attachment/12415768/appendDesign2.pdf].
was:
In order to support read consistency, DFSClient needs the file length at the
file opening time.
For more details, see Section 4 in the [append design
doc|https://issues.apache.org/jira/secure/attachment/12415768/appendDesign2.pdf].
In order to support reading a file when it is being written. I suggest to have
the following changes:
- DFSClient obtains all the block lengths from the namenode for the blocks is
not under construction. Note that only the last block is possibly under
construction. Other blocks must be finalized.
- For the last block, if it is under construction, DFSClient obtains the block
length from one of the datanode.
> When opening a file for read, make the file length avaliable to client.
> -----------------------------------------------------------------------
>
> Key: HDFS-570
> URL: https://issues.apache.org/jira/browse/HDFS-570
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: hdfs client
> Affects Versions: Append Branch
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
> Fix For: Append Branch
>
>
> In order to support read consistency, DFSClient needs the file length at the
> file opening time. In the current implmentation, DFSClient obtains the file
> length at the file opening time but the length is inaccurate if the file is
> being written.
> For more details, see Section 4 in the [append design
> doc|https://issues.apache.org/jira/secure/attachment/12415768/appendDesign2.pdf].
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