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https://issues.apache.org/jira/browse/SSHD-1078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17196270#comment-17196270
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Lyor Goldstein commented on SSHD-1078:
--------------------------------------
{quote}
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.
{quote}
I don't see why this would be necessary - you need +one+ {{SshClient}} in your
entire application and +different+ {{ClientSession}}-s for each node. I don't
see how having different clients would yield the behavior you claim to have
seen. It may be the case that you need to configure larger NIO2 workers thread
pool or tweak other parameters, but one {{SshClient}} instance should suffice...
> 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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