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https://issues.apache.org/jira/browse/HADOOP-14600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16267246#comment-16267246
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Chris Douglas commented on HADOOP-14600:
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bq. replace `listLocatedStatus` call with `listStatusIterator` because it
returns FileStatus rather than LocatedFileStatus and that doesn't trigger all
the getPermission() mess at all
Good point. Unfortunately, for everything accepted by the filter (which
defaults to accepting everything, IIRC), we double the RPCs if the client
subsequently asks for locations. That's bad for HDFS, but irrelevant to the
local FS and object stores that don't report locality information.
[~myapachejira], have you had a chance to verify the patch, yet?
> LocatedFileStatus constructor forces RawLocalFS to exec a process to get the
> permissions
> ----------------------------------------------------------------------------------------
>
> Key: HADOOP-14600
> URL: https://issues.apache.org/jira/browse/HADOOP-14600
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.7.3
> Environment: file:// in a dir with many files
> Reporter: Steve Loughran
> Assignee: Ping Liu
> Attachments: HADOOP-14600.001.patch, HADOOP-14600.002.patch,
> HADOOP-14600.003.patch, HADOOP-14600.004.patch, HADOOP-14600.005.patch,
> HADOOP-14600.006.patch, HADOOP-14600.007.patch, HADOOP-14600.008.patch,
> HADOOP-14600.009.patch, TestRawLocalFileSystemContract.java
>
>
> Reported in SPARK-21137. a {{FileSystem.listStatus}} call really craws
> against the local FS, because {{FileStatus.getPemissions}} call forces
> {{DeprecatedRawLocalFileStatus}} tp spawn a process to read the real UGI
> values.
> That is: for every other FS, what's a field lookup or even a no-op, on the
> local FS it's a process exec/spawn, with all the costs. This gets expensive
> if you have many files.
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