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https://issues.apache.org/jira/browse/HADOOP-14600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16265476#comment-16265476
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Ohad Raviv commented on HADOOP-14600:
-------------------------------------
I'm not sure I was clear enough in the above comment.
I totaly agree with your current patch, but I'm saying that the initiator of
all this mess from SPARK-21137 is org.apache.hadoop.mapred.FileInputFormat with
the following code:
{code}
for (FileStatus globStat: matches) {
if (globStat.isDirectory()) {
RemoteIterator<LocatedFileStatus> iter =
fs.listLocatedStatus(globStat.getPath());
while (iter.hasNext()) {
LocatedFileStatus stat = iter.next();
if (inputFilter.accept(stat.getPath())) {
if (recursive && stat.isDirectory()) {
addInputPathRecursively(result, fs, stat.getPath(),
inputFilter);
} else {
result.add(stat);
}
}
}
} else {
result.add(globStat);
}
}
{code}
All I'm suggesting is to replace `listLocatedStatus` call with
`listStatusIterator` because it returns FileStatus rather than
LocatedFileStatus and that doesn't trigger all the getPermission() mess at all.
testing that localy (on Mac) caused the test to run in less than a second
instead of about 30 seconds for about 10000 files.
> 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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