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https://issues.apache.org/jira/browse/HDFS-3051?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13236848#comment-13236848
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Colin Patrick McCabe commented on HDFS-3051:
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Hi Dhruba,
This sounds interesting. One thing I don't completely understand about your
proposed API is whether you will have multiple (position, length) pairs as
inputs. Traditionally, scatter-gather implies being able to read multiple
locations at once, like in ''preadv(2)''. However, I only see one position,
length argument in your readFullyScatterGather function.
Also, it seems to me that by mmapping at a fixed address, you could create a
single contiguous buffer rather than forcing the user to deal with multiple
buffers for a single HDFS file.
C.
> A zero-copy ScatterGatherRead api from FSDataInputStream
> --------------------------------------------------------
>
> Key: HDFS-3051
> URL: https://issues.apache.org/jira/browse/HDFS-3051
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs client
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
>
> It will be nice if we can get a new API from FSDtaInputStream that allows for
> zero-copy read for hdfs readers.
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