X11 / KDE Plasma 5 periodically freezes when I use GUI app inside LXC container
Hi Everybody ;-),
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TL;DR: Could you please help me to get logs / trace or debug X (or KDE Plasma 5)
that is freezing when I run (and actively use) X app inside LXC container?
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I'm trying to run GUI apps inside LXC container. I know that there are other
ways (snapd) but I really like the idea of LXC...
I followed the following guide:
https://gudok.xyz/lxcdeb/#_x11_applications_via_unix_socket
since it is almost exactly mirrors my setup.
My setup is:
- Debian Buster with KDE Plasma 5 with LXC container running
Debian 10, Debian 11 and Ubuntu 20.04 (I tested them all)
- I have same user in the container (same username and UID) as outside the
container with 1:1 UID mapping for this user.
I also tried to run GUI apps as root inside the container.
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lxc.idmap = u 0 100000 1000
lxc.idmap = g 0 100000 1000
lxc.idmap = u 1000 1000 1
lxc.idmap = g 1000 1000 1
lxc.idmap = u 1001 101001 64535
lxc.idmap = g 1001 101001 64535
lxc.mount.entry = /tmp/.X11-unix tmp/.X11-unix none ro,bind,create=dir 0 0
lxc.environment = DISPLAY=:0
lxc.environment = XAUTHORITY=/home/my_user_name/.Xauthority
# optional (works both with and without this):
lxc.mount.entry = /dev/dri dev/dri none bind,optional,create=dir
lxc.mount.entry = /dev/snd dev/snd none bind,optional,create=dir
lxc.mount.entry = /dev/video0 dev/video0 none bind,optional,create=file
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I was pleasantly surprised that after following the guide I was able
very quickly lunch GUI apps.
The problem that I'm facing is that when I start using the app my
desktop sometimes
completely freeze for approx 30sec. I tested "retext", "meld" and "VSCodium"
and a few other apps... It's all the same.
I know that it's only GUI (not the Linux) that freezes. For example
when I played video in VLC outside of the container and the freeze
happened - the VLC window froze with rest of the screen but I still heard
the audio.
It usually takes 30sec and then the desktop unfreeze and everything is
fine again.
During the freeze I can see / move with mouse cursor and when I click on for
example inactive window then the window becomes active after the freeze
which tells me that the desktop responds but I can’t see the change
during the freeze.
I'm not asking anyone to debug this complicated setup since I
understand that it's
complicated. There are too many layers - Xorg, KDE Plasma, LXC and
it's difficult to say what exactly is misbehaving.
Can somebody please just tell me how to narrow down to app/configuration
that is causing issues?
I tried following:
- Host: tail --follow /var/log/Xorg.0.log
- Host: sudo journalctl --follow
- Inside LXC cont.: journalctl --follow
But I don't get anything interesting when/after the freeze happens.
Thank you very much for any suggestions.
JR
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