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https://issues.apache.org/jira/browse/SSHD-1217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17434237#comment-17434237
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Thomas Wolf commented on SSHD-1217:
-----------------------------------
{quote}
the front-end has an SftpFileSystemProvider configured to proxy remote sftp
traffic to a backend Apache SSHD server.
{quote}
I think I see what's going on. {{DirectoryHandle}} uses the plugged-in file
system to list the directory via standard java.io.nio.Files operations. That
may be fine if the plugged file system is local, but if it is itself a remote
file system, the Apache MINA sshd implementation of the file system is super
inefficient. It gets the file attributes from the other end and then forgets
them right away, and then fetches them one-by-one again.
I think I can do something about that.
> Slow performance listing huge number of files on Apache SSHD server
> -------------------------------------------------------------------
>
> Key: SSHD-1217
> URL: https://issues.apache.org/jira/browse/SSHD-1217
> Project: MINA SSHD
> Issue Type: Improvement
> Affects Versions: 2.6.0
> Reporter: Roberto Deandrea
> Priority: Minor
> Attachments: trace.ssh-frontend-sftplist.finest.log.zip
>
>
> Hi Thomas,
> I noted slow performance listing files on the front-end Apache SSHD server in
> the same scenario as https://issues.apache.org/jira/browse/SSHD-1215
> The front-end Apache SSHD server is configured with a Filesystem built upon
> SFTPFileSystemProvider to proxy files to an Apache SSHD back-end server.
>
> In the /inbox folder of the Apache SSHD backend server I have 2000 files.
> The client sftp ls commands take 2 secs on the backend Apache SSHD server,
> instead it takes about 48 secs on the front-end Apache SSHD server.
> For greater number of files in the /inbox folder times are getting worse.
>
> I have full traces of sftp list commands to front-end Apache SSHD server
> that is attached to this jira.[^trace.frontend.sshd.log.zip]
> I looked through the traces on the front-end server and it seems to me that
> for every files in the folder the sftp client on the front-end server creates
> a SSH_MSG_CHANNEL_DATA generating tcp traffic that slow down the performance
> of the list command.
> Obviously this does not happen when a sftp client connects directly to the
> backend Apache SSHD server.
> Can you take a look at traces on the front-end Apache SSHD server ?
> Do you think it's possbile change something to improve performance of list
> files in this situation ?
>
> Thanks in advance
>
> Kind Regards
> Roberto
>
>
>
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