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Hadoop QA commented on HDFS-202:
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-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12451084/hdfsListFiles3.patch
against trunk revision 982091.
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 15 new or modified tests.
-1 patch. The patch command could not apply the patch.
Console output: http://hudson.zones.apache.org/hudson/job/Hdfs-Patch-h2.grid.sp2.yahoo.net/228/console
This message is automatically generated.
> Add a bulk FIleSystem.getFileBlockLocations
> -------------------------------------------
>
> Key: HDFS-202
> URL: https://issues.apache.org/jira/browse/HDFS-202
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Arun C Murthy
> Assignee: Hairong Kuang
> Fix For: 0.22.0
>
> Attachments: hdfsListFiles.patch, hdfsListFiles1.patch, hdfsListFiles2.patch,
hdfsListFiles3.patch
>
>
> Currently map-reduce applications (specifically file-based input-formats) use FileSystem.getFileBlockLocations
to compute splits. However they are forced to call it once per file.
> The downsides are multiple:
> # Even with a few thousand files to process the number of RPCs quickly starts getting
noticeable
> # The current implementation of getFileBlockLocations is too slow since each call
results in 'search' in the namesystem. Assuming a few thousand input files it results in that
many RPCs and 'searches'.
> It would be nice to have a FileSystem.getFileBlockLocations which can take in a directory,
and return the block-locations for all files in that directory. We could eliminate both the
per-file RPC and also the 'search' by a 'scan'.
> When I tested this for terasort, a moderate job with 8000 input files the runtime halved
from the current 8s to 4s. Clearly this is much more important for latency-sensitive applications...
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