[clug] KDE desktop kinda freezing

Bob Edwards bob at cs.anu.edu.au
Mon Feb 10 01:02:50 UTC 2020

On 9/2/20 5:43 pm, Tony Lewis via linux wrote:
> On 9/2/20 8:26 am, Robert Edwards via linux wrote:
>> On 9/2/20 12:11 am, Tony Lewis via linux wrote:
>>> I've been running the current Kubuntu version for the last few 
>>> months, and I find that every so often it freezes.  I'm trying to 
>>> find out what causes it and what I can do to fix it.
>>> The symptoms are:
>>>   * the mouse cursor moves freely, but no actions do anything to windows
>>>   * the keyboard does nothing
>>>   * the desktop doesn't change, including panels with clocks in it
>>>   * audio keeps playing (e.g. spotify)
>>>   * I cannot successfully save my Windows VM from the command line (more
>>>     below)
>>> I can switch to text consoles, log in and do stuff.  Nothing unusual 
>>> is showing up in htop (i.e. no excessive disk or CPU usage, no 
>>> excessive memory, no meaningful swapping).
>>> Things I've tried:
>>>   * killing processes like the obvious contenders (for me) of Firefox,
>>>     Thunderbird and VirtualBox
>>>   * killing and restarting plasmashell
>>>   * looking for other desktopy processes and killing them
>>>   * starting an xterm from the command line into the desktop -
>>>     'DISPLAY=:0.0 xterm' - from the command line it looks like it
>>>     starts, but no change to the desktop
>>> The worst part of this is any loss of documents in my work Windows 
>>> VM, where I am not diligent in saving documents sometimes.  I try the 
>>> 'savestate' command, which works under normal circumstances, but 
>>> under this frozen desktop scenario, it doesn't complete; it freezes 
>>> up somewhere between 90 and 100% even if I leave it for hours.
>>> Eventually I have to pretty much just restart.
>>> What can I do to try and debug?
>>> Tony
>> Hi Tony,
>> Not sure about KDE/plasmashell, but most of your symptoms are not
>> inconsistent with the X focus remaining on a broken alert panel which
>> may be hidden under other windows. I think your "looking for other
>> desktopy processes and killing them" should have resolved this -
>> how confident are you that you have found all of them?
> Not at all.  There are so many processes that the thought of listing 
> them, picking one, killing it, switching back to the desktop to check, 
> rinse and repeat, is too onerous, and I end up just restarting.
> I'd be happy to consider processes if you can recommend any.

Hi Tony - Nope. I have nothing to suggest there...

>> One thing to try might be to start another GUI in another Virtual
>> Terminal (doesn't even have to be KDE), and maybe run VirtualBox
>> in there for a while. If the issue is with the graphics driver/
>> hardware, then likely both desktops will freeze - if it is only
>> with KDE, then only the KDE one should have issues. This won't tell
>> you what the problem is, but will assist you in finding the fault.
>> Copy-pasting between desktops is problematic, but using the file
>> system should provide some work-arounds for that.
> This is a great idea, in principle.  I just tried it and it started 
> working fine.  I had KDE on one and `startx` happened to bring up XFCE 
> on the other.
> However they conflicted with each other.  If I switched away from KDE to 
> XFCE and then back, the KDE session was logged out, with all windows 
> killed, requiring me to log in and restart my apps.  I tried defining 
> and using separate XDG_CONFIG_HOME, XDG_DATA_HOME, XDG_CACHE_HOME and 
> XDG_RUNTIME_DIR variables (which got populated, so they worked), but 
> still the KDE desktop got killed reverting back to a login screen.
>> One of many links to help you do it:
>> https://journalxtra.com/linux/desktop/multiple-desktops-on-one-linux-pc-now-thats-greedy/ 
> One suggestion from your link was to use separate users.  I could do 
> that, but it would take some effort to move the virtual machine over. 
> Do-able but undesirable.

I definitely recommend running as separate users. Maybe pick on some
other app to run in the second GUI, like a web browser etc. Running
multiple GUIs out of the same home dir. simultaneously can be...

Our student lab environment uses NFS for student home directories and
seeing some of the issues when students log into multiple machines
simultaneously is quite entertaining - the first few times...

I suggested VirtualBox for two reasons - one is the keyboard capture,
which always worries me... (although I use it frequently) and the other
is to be a little less disruptive to your work env. But pick anything
else you care to.

Bob Edwards.

> Thanks,
> Tony

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