krishnan created VFS-698:
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Summary: SFTP file attributes are fetched multiple times leading
to very slow directory listing
Key: VFS-698
URL: https://issues.apache.org/jira/browse/VFS-698
Project: Commons VFS
Issue Type: Bug
Affects Versions: 2.3
Reporter: krishnan
getChildren() applied on SftpFileObject is very slow compared to JSCH
implementation since the SftpATTRS which is readily available for the children
after an "ls" call is again fetched for each child file since they are
independently resolved. So if a directory contains 10 files, it results in 1
(ls) + 10 (stat) calls to server.
For a folder with 100 files (AWS), it took about 35 secs instead of 1.5 secs to
getChildren().
*doListChildrenResolved:*
{{final FileObject fo =
getFileSystem().resolveFile(getFileSystem().getFileSystemManager()}}
{{ .resolveName(getName(), UriParser.encode(name), NameScope.CHILD));}}
{{{color:#FF0000}((SftpFileObject)
FileObjectUtils.getAbstractFileObject(fo)).setStat(stat.getAttrs());{color}}}
The resolveFile call, creates a SftpFileObject and calls its resolve method,
which results in getting the (stats) SftpATTRS for each child file. This stat
is already available as part of the 'ls' call we made. The setStat call above
(highlighted is red) is redundant, since stat for each child file is already
fetched one at a time.
The solution would be to avoid getting the stat for each child file after an
'ls' call. May be, the framework makes it difficult to do this easily.
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