[jira] [Comment Edited] (SSHD-1078) SCP/SFTP failed for big file upload

["min yun law (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SSHD-1078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17196542#comment-17196542 ] 

min yun law edited comment on SSHD-1078 at 9/15/20, 8:32 PM:
-------------------------------------------------------------

{code:java}
"I don't see why this would be necessary - you need one SshClient in your entire application and different ClientSession-s for each node."{code}
That was we did to use Jsch and Mina SSHD, but Mina SSHD has problem when one ClientSession per node for all executing and SCP/SFTP operations. 

I have to allocate a new ClientSession for a SCP/SFTP file operation when the file are bigger.

If share the same ClientSession per node, channel exception will be generated. 

we only use mina sshd for client side, not for ssh server. openssh is being used for ssh server.

 


was (Author: minlaw):
{code:java}
"I don't see why this would be necessary - you need one SshClient in your entire application and different ClientSession-s for each node."{code}
That was we did to use Jsch and Mina SSHD, but Mina SSHD has problem when one ClientSession per node for all executing and SCP/SFTP operations. 

I have to allocate a new ClientSession for a SCP/SFTP file operation when the file are bigger.

If share the same ClientSession per node, channel exception will be generated. 

 

> SCP/SFTP failed for big file upload
> -----------------------------------
>
>                 Key: SSHD-1078
>                 URL: https://issues.apache.org/jira/browse/SSHD-1078
>             Project: MINA SSHD
>          Issue Type: Bug
>    Affects Versions: 2.5.1
>            Reporter: min yun law
>            Priority: Major
>
> Trying to merge product from jsch to mina sshd that keep the same SSH architecture (lets call SessionPool) which for each remote node, there is only one session object and limited channels (<=8) for executing commands and file operations. The SessionPool  manages the session/channels for nodes  and make sure only 8 threads(ssh channels) per node that can be run concurrently. This architecture works for Jsch for many years, but when using mina sshd, this architecture wont work when  with upload big file, we always see following exception:
> {code:java}
> java.io.EOFException: Channel is being closed
> at org.apache.sshd.common.channel.AbstractChannel$2.<init>(AbstractChannel.java:794)
> at org.apache.sshd.common.channel.AbstractChannel.writePacket(AbstractChannel.java:792)
> at org.apache.sshd.common.channel.ChannelAsyncOutputStream.doWriteIfPossible(ChannelAsyncOutputStream.java:168)
> at org.apache.sshd.common.channel.ChannelAsyncOutputStream.writePacket(ChannelAsyncOutputStream.java:70)
> at org.apache.sshd.client.subsystem.sftp.impl.DefaultSftpClient.send(DefaultSftpClient.java:292)
> at org.apache.sshd.client.subsystem.sftp.impl.SftpOutputStreamAsync.flush(SftpOutputStreamAsync.java:210)
> at org.apache.sshd.client.subsystem.sftp.impl.SftpOutputStreamAsync.write(SftpOutputStreamAsync.java:141)
> {code}
> From SSH server log, we see follow error:
> {code:java}
> Aug 19 15:56:38 xxxx sftp-server[202217]: error: Unknown message 0
> Aug 19 15:56:38 xxxx sftp-server[202217]: error: msg_len 0 < consumed 1
> {code}
> other client side exceptions by mina sshd as:
> org.apache.sshd.common.channel.WindowClosedException: Already closed: Window[client/remote](ChannelExec[id=79, recipient=1]-ClientSessionImp
>  
> ----
> After many tries, finally I found that for big file upload/download, I have to give its own SshClient/ClientSession objects and then there will  no such channel closing exception during file upload.  
> That means we cannot share the same SshClient and ClientSession object per remote node to execute commands and file operations, and there may has bug in ClientSession when handle channels in this situation.
> the reason that we like to share the same SshClient/ClientSession for the same remote node is to manage the session/channels and close them when no usage, also to reduce the cost to allocate those objects. 
>  
>  



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