changing skin or waveform renderer crashes on Ubuntu 20.04

[mixxxbot]

Reported by: shaban238
Date: 2020-04-16T22:55:05Z
Status: Fix Released
Importance: High
Launchpad Issue: lp1873367
Attachments: mixxx.crash, crash_20.04.backtrace, [Crash from Deere to Tango.txt](https://bugs.launchpad.net/bugs/1873367/+attachment/5394765/+files/Crash from Deere to Tango.txt)

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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

[mixxxbot]

Commented by: shaban238
Date: 2020-04-16T22:55:05Z
Attachments: mixxx.crash

[mixxxbot]

Commented by: ronso0
Date: 2020-04-21T12:28:04Z

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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

[mixxxbot]

Commented by: shaban238
Date: 2020-04-22T16:21:11Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-05-03T19:45:41Z
Attachments: crash_20.04.backtrace

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Can confirm this with a local build on Ubuntu Studio 20.04

[mixxxbot]

Commented by: daschuer
Date: 2020-05-03T20:12:49Z

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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?

[mixxxbot]

Commented by: ronso0
Date: 2020-05-03T20:38:35Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-05-03T20:58:13Z

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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

[mixxxbot]

Commented by: daschuer
Date: 2020-05-03T21:02:27Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-05-03T21:08:04Z

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

[mixxxbot]

Commented by: Holzhaus
Date: 2020-06-03T20:28:27Z

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

[mixxxbot]

Commented by: ronso0
Date: 2020-06-07T21:02:42Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-06-08T14:22:51Z

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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.

[mixxxbot]

Commented by: gwarchive
Date: 2020-07-22T04:06:15Z
Attachments: [Crash from Deere to Tango.txt](https://bugs.launchpad.net/mixxx/+bug/1873367/+attachment/5394765/+files/Crash from Deere to Tango.txt)

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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

[mixxxbot]

Commented by: ronso0
Date: 2020-07-28T14:55:20Z

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

[mixxxbot]

Commented by: ronso0
Date: 2020-08-25T15:07:54Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-08-25T15:11:58Z

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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.

[mixxxbot]

Commented by: ronso0
Date: 2020-10-01T22:43:14Z

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may be fixed by #3144

[mixxxbot]

Commented by: ronso0
Date: 2020-10-01T22:46:53Z

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

[mixxxbot]

Commented by: temkaveter
Date: 2020-11-02T09:55:29Z

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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.

[mixxxbot]

Commented by: temkaveter
Date: 2020-11-02T09:58:59Z

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

[mixxxbot]

Commented by: ronso0
Date: 2020-11-02T11:07:28Z

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@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 #3144 ?
Switching skins was reported to work fine for all skins with those.

[mixxxbot]

Issue closed with status Fix Released.