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Posted to dev@mina.apache.org by "Zhenliang Su (JIRA)" <ji...@apache.org> on 2018/03/28 02:13:00 UTC
[jira] [Comment Edited] (SSHD-812) support asynchronization mode
for sftp subsystem
[ https://issues.apache.org/jira/browse/SSHD-812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16416593#comment-16416593 ]
Zhenliang Su edited comment on SSHD-812 at 3/28/18 2:12 AM:
------------------------------------------------------------
Thanks for your guide.:)
I analyzed the behavior of the filezilla client. When it want to read a file from sftp server, it send multiple SSH_FXP_READ request packet with different id and offset field before any SSH_FXP_DATA packet response. It want to read multiple block at the same time, not one by one, but `SftpSubsystem` have to process each request one by one. I think this is the bottleneck.
!doRead.png!
When processing SSH_FXP_READ or SSH_FXP_WRITE request, we can associate each reply to an SFTP command through `id` field.
was (Author: smoking):
Thanks for your guide.:)
I analyzed the behavior of the filezilla client. When it want to read a file from sftp server, it send multiple SSH_FXP_READ request packet with different id and offset field before any SSH_FXP_DATA packet response. It want to read multiple block at the same time, not one by one, but `SftpSubsystem` have to process each request one by one. I think this is the bottleneck.
!doRead.png!
When processing SSH_FXP_READ or SSH_FXP_WRITE request, we can associate each reply to an SFTP command through `id` field.
> support asynchronization mode for sftp subsystem
> ------------------------------------------------
>
> Key: SSHD-812
> URL: https://issues.apache.org/jira/browse/SSHD-812
> Project: MINA SSHD
> Issue Type: New Feature
> Affects Versions: 1.7.0
> Environment: java1.8, linux
> Reporter: Zhenliang Su
> Assignee: Goldstein Lyor
> Priority: Major
> Labels: asynchronous, sftp
> Attachments: Main.java, doRead.png
>
>
> I used SSHD as a middleman between client and target sftp server.
> I found that, when filezilla client directly connect to the target sftp server, it transfers fast. When filezilla client connect to the middleman, it transfers slow.
> I analyzed the source code of org.apache.sshd.server.subsystem.sftp.SftpSubsystem#doRead, and I found it behaves like block mode, and client's other SSH_FXP_READ request blocked in the same thread.
>
> my middleman code:
> [^Main.java]
>
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