I'm running Guacamole on CentOS 7.5 with xrdp.
Recently I discovered that gnome-shell crashes from SIGABRT when I start xterm on a GNOME desktop running in an xrdp Xvnc session.
"[abrt] gnome-shell: gnome-shell killed by SIGABRT"
It only happens when I connect to an Xvnc session with Guacamole.
No issues when initiating xrdp Xvnc or Xorg sessions from a Windows, Mac or Linux client (vinagre).
No issues with xrdp Xorg sessions (with any RDP client including Guacamole).
Just the Guacamole client seems to give me a headache in combination with xrdp/Xvnc.
Has anyone else been experiencing the same or a similar issue?
On Sat, Jul 7, 2018 at 2:41 AM Stefan M. Radman <[hidden email]> wrote:
This is definitely an interesting little corner case you've run into. When this happens, is it just gnome-shell that crashes, or does the entire session (Guacamole connection, Xvnc/XRDP, et al)? Any chance you can start up gdb or strace on/with that gnome-shell instance and catch the output of what's causing it to crash?
First, gnome-shell crashes (you notice by the desktop going black and the window decorations disappearing) but ultimately the whole xrdp/Xvnc session dies (Guacamole asks me if I want to logout or reconnect).
Sometimes it takes a little bit longer and I can still interact with window contents while the window manager is long gone but in the end it just dies on me.
There are lots of [abrt] emails and they contain stack traces.
See the last one further below. The previous ones look pretty much the same.
I've never run xrdp/Xvnc or gnome-shell under gdb or strace but if you have a hint for me on how to do this I'll give it a try.
# cat /var/spool/mail/root | fgrep -A1 function_name | cut -d: -f3- | while read func; do read file; read stuff; echo $file $func; done | tail -24
On Sat, Jul 7, 2018 at 6:56 PM Stefan M. Radman <[hidden email]> wrote:
Sorry for the delay in responding, here. It sounds like the most likely cause is some difference between how guacd is establishing the VNC connection and the other VNC clients. Not sure if it's a quality, encoding, etc., sort of thing, but that's my best guess. Any chance you can try different settings for the non-Guacamole VNC client and see if you're able to reproduce it at all with that - things like color depth, encoding, quality, etc.? Also might want to play with the settings in Guacamole that you can adjust and see if any adjustments to that resolve the issue.
I have not been able to reproduce the issue with another client but found two ways to resolve the issue for Guacamole:
A. Switching the Guacamole RDP session to "Color Depth: True Color (24-bit)"
B. Uncomment xserverbpp=24 in the [Xvnc] section of /etc/xrdp.ini
Either of the two avoids the crash of gnome-shell.
The default color depth of xrdp/Xvnc seems to be 32 bit.
Recently I've seen issues with widgets of cross-platform toolkits like Java Swing or Tcl/Tk not displaying or displaying incorrectly on Xvnc based GNOME desktops running under xrdp with default settings. Most of them looked like they were related to transparency.
All of them were resolved by setting the color depth of the RDP session to 24.
My Xvnc server is is part of the CentOS7 package tigervnc-server-minimal-1.8.0-17 and its man page reads
Specify the pixel depth in bits of the desktop to be created.
Default is 24, other possible values are 8, 15, and 16 - anything else
is likely to cause strange behaviour by applications.
Strange and unexpected behaviour indeed.
Seems like Xvnc is not buit for 32 bit.
xserverbpp=24 is my new default.
CONFIDENTIALITY NOTICE: This communication may contain privileged and confidential information, or may otherwise be protected from disclosure, and is intended solely for use of the intended recipient(s). If you are not the intended recipient of this communication, please notify the sender that you have received this communication in error and delete and destroy all copies in your possession.
|Free forum by Nabble||Edit this page|