Subject: RE: SFTP transfer hangs when the server connection has high latency RTT around 500 ms and 30% packet loss

RE: SFTP transfer hangs when the server connection has high latency RTT around 500 ms and 30% packet loss

From: Ketul Barot <kbarot_at_parallelwireless.com>
Date: Thu, 30 May 2019 14:39:45 +0000

Hi,

Can someone from libssh2 community please help me with this issue?

Thanks,
Ketul

From: Ketul Barot
Sent: Tuesday, March 05, 2019 10:25 AM
To: libssh2-devel_at_cool.haxx.se
Subject: RE: SFTP transfer hangs when the server connection has high latency RTT around 500 ms and 30% packet loss

Hi,

For some reason I am not able to reproduce the hang with sftp_write_nonblock.c but I did find the same thing happen with the curl. I have enabled the debug option and added the libssh2_trace as mentioned by you.

Attaching the log file. It has both libcurl debug messages & libssh2 debug messages. Please take a look at the log file and I will try again to reproduce the hang with sftp_write_nonblock.c example. I will send the debug log for that once I reproduce the issue.

Thanks,
Ketul

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Subject: libssh2-devel Digest, Vol 117, Issue 1

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Today's Topics:

1. Re: SFTP transfer hangs when the server connection has high
latency RTT around 500 ms and 30% packet loss (Peter Stuge)


----------------------------------------------------------------------

Message: 1
Date: Fri, 1 Mar 2019 17:01:14 +0000
From: Peter Stuge <peter_at_stuge.se<mailto:peter_at_stuge.se>>
To: libssh2-devel_at_cool.haxx.se<mailto:libssh2-devel_at_cool.haxx.se>
Subject: Re: SFTP transfer hangs when the server connection has high
latency RTT around 500 ms and 30% packet loss
Message-ID: <20190301170114.22805.qmail_at_stuge.se<mailto:20190301170114.22805.qmail_at_stuge.se>>
Content-Type: text/plain; charset=us-ascii

Hi,

Ketul Barot wrote:
> To eliminate if libssh2 is the real reason for the hang. I used
> sftp_write_nonblock.c as an example from the libssh2 examples and
> used that to upload a file in my setup and here to I am seeing the
> same behavior that the sftp_write_nonblock application get's hung.
>
> Would greatly appreciate if some one can look in to this. Also, I
> can provide any extra debug information that would help to resolve
> this issue.

Yes, you will have to provide debug information for anyone to be able
to analyze your problem.

Ideally build the current libssh2 master code with debug messages
enabled, and add a call like libssh2_trace(session, ~0); in
sftp_write_nonblock.c maybe after the libssh2_userauth_ calls, before
the first libssh2_sftp_ call.

Then send the full output from that program for a run where the error
happens to the list. Please log to a text file and attach that file
to your mail, so that all information is kept intact. Thanks!


//Peter


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Received on 2019-05-30