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https://issues.apache.org/jira/browse/NET-455?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13237019#comment-13237019
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Nicolas commented on NET-455:
-----------------------------
Thanks for your help !
The two cases where observed separately, and not in a row, so no caching
possible. I did many runs like ABAABBA (but each time I stopped the JVM and
restart my soft with the other filter method) and so I could reproduce the case
each time.
However, I looked the source code of FTPClient, and you are right, no
difference.
Maybe I have some sort of answer, but I'm really not sure :
I call
{code} files = ftpClient.listFiles("./", ftpFileFilter); {code}
So it calls the function
{code}initiateListParsing(String parserKey, String pathname) {code}
with the pathname not null, whereas in the "fast" case, the pathname is null.
So I do "LIST -a ./" instead of a "LIST -a" (if I'm right).
I'll dig into it on monday, trying null path or getFiles("./"), I'll come back
with the results!
> FTPClient listFiles(FTPFileFilter) can be faster...
> ---------------------------------------------------
>
> Key: NET-455
> URL: https://issues.apache.org/jira/browse/NET-455
> Project: Commons Net
> Issue Type: Improvement
> Components: FTP
> Affects Versions: 3.0.1
> Environment: all
> Reporter: Nicolas
> Priority: Minor
> Labels: ftpclient, listFiles
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> I tested two ways of sorting files on a remote FTP server with many files ( >
> 110 000). Both of these use the FtpFileFilter class (with a test on the
> extension filename... very simple).
> The first one is the conventionnal =>
> {code}
> files = ftpClient.listFiles("./", ftpFileFilter);
> {code}
> It takes about 90 seconds ...
> the second one is ... nearly as simple as the first one :
> {code}
> FTPFile [] allFilesListed = ftpClient.listFiles();
> files = FTPFileFilterWithExtension.fastFilter(ftpFileFilter, allFilesListed);
> {code}
> The function FTPFileFilterWithExtension.fastFilter() call the same
> ftpFileFilter :
> {code}
> public static FTPFile [] fastFilter(FTPFileFilter filter, FTPFile
> ftpFileArray []) {
> ArrayList<FTPFile> listOfFTPFiles = new ArrayList<FTPFile>();
> for (FTPFile ftpf : ftpFileArray) {
> boolean accepted = filter.accept(ftpf);
> if (accepted) {
> listOfFTPFiles.add(ftpf);
> }
> }
> FTPFile resultArray [] = new FTPFile[listOfFTPFiles.size()];
> return listOfFTPFiles.toArray(resultArray);
> }
> {code}
> The second method is EIGHT times faster than the first one ... and I don't
> really understand why...
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