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https://issues.apache.org/jira/browse/HDFS-14440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16832735#comment-16832735
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Ayush Saxena commented on HDFS-14440:
-------------------------------------
Back to the same place. :(
Firstly, If we do so, in case of successful file write, it shall go over all
the destinations, so it will take N time (N being number of namespaces) and
successful writes are more than failures due to File being Already exist.
Secondly, Not sure we can get the location to trigger from getFileInfo() as we
got from blockLocation. Or even doubt if its worth it.
Thirdly, In the previous scenario too, in case of empty file you need to make
two calls, 2 time Unit, if the file is empty.
> RBF: Optimize the file write process in case of multiple destinations.
> ----------------------------------------------------------------------
>
> Key: HDFS-14440
> URL: https://issues.apache.org/jira/browse/HDFS-14440
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Ayush Saxena
> Assignee: Ayush Saxena
> Priority: Major
> Attachments: HDFS-14440-HDFS-13891-01.patch,
> HDFS-14440-HDFS-13891-02.patch, HDFS-14440-HDFS-13891-03.patch,
> HDFS-14440-HDFS-13891-04.patch, HDFS-14440-HDFS-13891-05.patch,
> HDFS-14440-HDFS-13891-06.patch
>
>
> In case of multiple destinations, We need to check if the file already exists
> in one of the subclusters for which we use the existing getBlockLocation()
> API which is by default a sequential Call,
> In an ideal scenario where the file needs to be created each subcluster shall
> be checked sequentially, this can be done concurrently to save time.
> In another case where the file is found and if the last block is null, we
> need to do getFileInfo to all the locations to get the location where the
> file exists. This also can be prevented by use of ConcurrentCall since we
> shall be having the remoteLocation to where the getBlockLocation returned a
> non null entry.
>
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