[X2Go-User] Graphical apps stalling in suspended session

[Matthew L. Dailey]

We ran into an odd issue recently that feels like a bug, but I wanted to throw it out to the community to see if anyone else has seen this or has any ideas.

When we run a graphical app in xfce via X2Go and then suspend the session, the app continues to run, but significantly slower than if we remain connected. If we resume the session while the app is still running, it resumes its normal speed. This issue seems identical to bug 673 (<http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=673>), but this was closed because it was not reproducible.

The simplest way I found to reproduce this is to have gnuplot plot in a loop, so it takes a while. If I use this input file:

do for [a=1:200] {
  plot sin(x+a)
}

It runs in a reasonable amount of time while logged into an xfce x2go session:
$ time gnuplot plot.txt

real	0m6.059s
user	0m1.348s
sys	0m0.124s

If I use a sleep first and suspend so gnuplot runs in the suspended session, it takes much longer:
$ sleep 5; time gnuplot plot.txt

real	2m24.365s
user	0m1.516s
sys	0m0.176s

Another way to reproduce is to run glxgears and then suspend and resume. You’ll see that while suspended, the frame rate is significantly lower, but then resumes normal speed when the session is resumed.

Here are the particulars of the server:
OS: Xubuntu 14.04.3 (built this to test - we’re primarily seeing this on our Ubuntu 14.04.3 systems with xfce)
x2goagent: 2:3.5.0.32-0~668~ubuntu14.04.1
x2goserver: 4.0.1.19-0~1064~ubuntu14.04.1
x2goserver-extensions: 4.0.1.19-0~1064~ubuntu14.04.1
x2goserver-xsession: 4.0.1.19-0~1064~ubuntu14.04.1

Thanks for any help you can provide. Let me know if you have questions or need any other information.

-- 
Matthew L. Dailey
Senior Systems Engineer
Thayer School of Engineering
Dartmouth College