[X2Go-Dev] occurrence of sluggishness in X2Go

[John A. Sullivan III]

On Fri, 2012-06-01 at 08:32 +0200, Mike Gabriel wrote:
> Hi,
> 
> just for the record and to let people know about current work focus...
> 
> People (esp. John) have reported occurrences of a very sluggish  
> behaviour of various applications when run in X2Go sessions.
> 
> We developers can now confirm this. Ubuntu users reported this  
> earlier, Debian user can now also experience such a sluggishness.
> 
> Reproduce on Debian:
> 
>    * add squeeze-backports archive to your system
>    * install iceweasel (esr version)
> 
> This will drag in a libcairo from squeeze backports that is very  
> probably the cause for making some applications very slow within X2Go  
> sessions.
> 
> Libcairo is used in all GTK applications and is a layer between GTK  
> and the rendering backend (X11, OpenGL, ...). With some recent version  
> of libcairo the sluggishness got introduced...
> 
> @John: so it is not Nagle, I guess...
> 
> Compare: launch gnome-terminal (uses libcairo) on such a system and  
> xterm (uses direct X11 rendering). Now create some output on standard  
> out and then scroll back the shell history...
> 
> Alex has become aware of this on Linux Day Berlin and he has put it on  
> his list with high priority to find a solution/workaround for that.
> 
<snip>
Hmm . . . as I think about it, although I eagerly await this fix, I
believe we are looking at two separate issues.  We are still running
3.0.1 series on our production servers and clients because of this issue
(and some others).  However, I personally run the latest client from
heuler.  I have the problem on both the latest x2goserver and the old
3.0.1-5 x2goserver.  It appears to be a client and not a server issue
and appeared with the move to libssh.

The delay is not inconsequential.  We are not talking about a sese of
sluggishness with a 250ms delay.  We are talking about a 2 to 5 full
second delay for the final keystrokes or screens to appear.  Everything
else until the final bit is lightning fast even on WAN links - John