changing skin or waveform renderer crashes on Ubuntu 20.04

[shaban]

ubuntu studio 20.04 (beta), mixxx crashing when i try to change skin in preferences (interface)

also when trying to change waveform overview type from rgb to filtered

[ronso0 (ronso0)]

Can you please try to reproduce the crash when 20.04 is officially released?

If the bug persists, please attach a backtrace here.
https://www.mixxx.org/wiki/doku.php/creating_backtraces?s[]=gdb#linux_mac_os_x_with_xcode_4x

[shaban (shaban238)]

tomorrow ubuntu studio will be released, i will try it again even though i dont think it will make such a difference at this point.

[ronso0 (ronso0)]

Can confirm this with a local build on Ubuntu Studio 20.04

[Daniel Schürmann (daschuer)]

Is this the crash?
#0 0x0000000000000000 in ()

That's bad, because it is a pure QT call stack

Does it also happen if you start Mixxx with

--safeMode

Does Mixxx crash on startup if you manual edit the cfg file to a special skin or waveform setting?

[ronso0 (ronso0)]

Update:
it doesn't crash anymore after I set my wavefroms & overviews to RGB. From now on changing skins and overview/waveform types works flawlessly.

[ronso0 (ronso0)]

Yes, I did edit the cfg to LateNight Classic after it crashed a few times when changing away from Deere.
(changing the overview type also reloads the skin so that crash is just another symptom of the same cause)

I removed .mixxx/ and started over:
* initially there's no ResizableSkin line in the [Config] section anymore.
* Exiting Mixxx crashes it
* If I create that entry manually and set it to Deere it keeps crashing
* if I set it to any other skin, from the next start on Mixxx runs fine without any crashes whatsoever

[Daniel Schürmann (daschuer)]

OK, is there a single change that makes it crash again like changing to a GL type waveform?

Can you confirm that start Mixxx with a crashing setting works, and only changing the skin crashes Mixxx?

So maybe we have an issue when unloading and reloading a waveform.

[ronso0 (ronso0)]

...no, with --developer mode it starts crashing again when reloading the skin. I'll collect some more backtraces.

[Jan Holthuis (holthuis-jan)]

Can you check if this still happens with latest mesa 20.0.7? I cannot reproduce this anymore.

[ronso0 (ronso0)]

Unfortunately 20.0.7 is not yet available in Focal or Focal-backports repos.
Still crashing. I suggest we look closer why it is failing with Deere only.

[ronso0 (ronso0)]

I manually updated all mesa packages from 20.0.4 to 20.0.7 and rebuilt Mixxx with Qt 5.12.8 from Ubuntu repos.
Still crashing as soon as Deere gets involved.

[patchtheuniform (gwarchive)]

Two different, but similar backtraces changing from Deere to Tango and Deere to Shade. Attached to Tango. Shade was similar just with a different segfault reason.

Thread 1 "mixxx" received signal SIGSEGV, Segmentation fault.
0x00007ffff6f1f780 in QRegion::shared_empty () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5

[ronso0 (ronso0)]

FWIW:
With RGB(GLSLS) waveforms, changing from Tango to LateNight and back works fine.

[ronso0 (ronso0)]

More findings:
With Shade it seems to crash when there's a Singleton created from waveform.xml. As soon as waveform.xml is loaded in deck.xml directly switching to LateNight or Tango works.
That would fix the situation for Shade, but in Deere we need the waveform in two places.

[ronso0 (ronso0)]

I can't verify a relation to the waveform renderer type. Sometimes reloading works with RGB, then it crashes again. It worked a once with Filtered, then it crashed.

[ronso0 (ronso0)]

may be fixed by https://github.com/mixxxdj/mixxx/pull/3144

[ronso0 (ronso0)]

considering #3144 just a workaroud so I won't assing this to me.
Maybe someone comes up with a fix for the root cause...

[WhiteWind (temkaveter)]

Ubuntu 20.04 (not Studio). The bug is the same here: all themes are not switching. But I can switch theme manually (for example, I changed in in config.xml to Tango and started mixxx again - the theme was Tango, but I have tried to switch back to Deere from Preferences - and it crushed again.
So, it only crashes when switching on the fly. Hope it can help.

[WhiteWind (temkaveter)]

Now I am back to Deere, switched through config.xml, working fine but waveform rendering is not working on Deere.

[ronso0 (ronso0)]

@WhiteWind
the affected skins are Deere and Shade.
Just to be sure: setting Tango and switching to LateNight and back to Tango works?

could yo try the skins from https://github.com/mixxxdj/mixxx/pull/3144 ?
Switching skins was reported to work fine for all skins with those.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/9929