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https://issues.apache.org/jira/browse/HDFS-7729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14319692#comment-14319692
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Zhe Zhang commented on HDFS-7729:
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[~libo-intel] Thank you for taking on the refactor task! I think it's a great
opportunity to "preview" the quality requirement when we eventually merge the
branch to trunk.
Just to clarify, I think the current patch (008) already has the [3 main steps
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https://issues.apache.org/jira/browse/HDFS-7729?focusedCommentId=14319136&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14319136]
required in striped writing. After the HDFS-7793 refactor, I think we'll be
able to leverage a major portion of it.
In subclassing {{DFSOutputStream}} we should try to minimize duplicate code.
For example, we should ideally append striping logic in override methods:
{code}
// DFSOutputStreamStriped
@Override
protected synchronized void writeChunk(byte[] b, int offset, int len,
byte[] checksum, int ckoff, int cklen) throws IOException {
addToCellBuffer();
super.writeChunk();
// Two extra steps are needed when a striping cell is full:
// 1. Forward the current index pointer
// 2. Generate parity packets if a full stripe of data cells are present
...
}
{code}
Again, great work so far by [~libo-intel] and reviewers. Let's take the time
and build the right client code for EC.
> Add logic to DFSOutputStream to support writing a file in striping layout
> --------------------------------------------------------------------------
>
> Key: HDFS-7729
> URL: https://issues.apache.org/jira/browse/HDFS-7729
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Li Bo
> Assignee: Li Bo
> Attachments: Codec-tmp.patch, HDFS-7729-001.patch,
> HDFS-7729-002.patch, HDFS-7729-003.patch, HDFS-7729-004.patch,
> HDFS-7729-005.patch, HDFS-7729-006.patch, HDFS-7729-007.patch,
> HDFS-7729-008.patch
>
>
> If client wants to directly write a file striping layout, we need to add some
> logic to DFSOutputStream. DFSOutputStream needs multiple DataStreamers to
> write each cell of a stripe to a remote datanode.
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