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Qtractor - adding a bus makes Qtractor crash

Dear Rui!

Using Qtractor v0.9.13 through v0.9.13.6 on Debian 10, I reproducable crash the program when I add a new midi-bus. It happens more often when I deal with lv2 plugins, but it also happens when i just simply create a new bus. Starting Qtractor from a terminal, it reports "memory access error". I am thankful for any ideas.

Best wishes and health to you and your family!

rncbc's picture

hi Michael, hope you're doing great, thanks

can you give us some more details on this?

maybe the precise steps you do, whether is an already existing session or does it occur every time on a bland new empty one?
where, when and which lv2 plugins in particular do you insert or is it on anyone, anytime?

i seem to have some rather total difficulty to reproduce the crash, but i'm sure you can manage to show me the right moves :)

stay safe and sane


ps. how are you getting it the latest on debian buster? is it you building from source git head? or is it from one of mine launchpad ppa's?

babarosa's picture

Hi Rui,
I compile your q-stuff by myselves. I didn't even know that such a ppa exists. I will install your version and investigate further, maybe it is again only a "lv2-issue".
I am using Debian 10 with Qt-version 5.11.3.
Thank you for your advices!
Greetings, Michael

rncbc's picture

can you try again on a most recent and latest git head, eg. qtractor >= ?


babarosa's picture

I tried today with v0.9.13.11git.11cf37, your package and self compiled (the only difference my version is built without vst3 support). Sadly, it didn't help.
I start with an empty project and I import a drum midi track (35 kb). Bus settings "master" -> "master". Connections are set via qjackctl (also tried your versions) to qsynth (also tried your version) and it works like a charm as I am used to it :-)

Now I add a second midi track and leave it empty. Double clicking on the tracks pane opens the settings dialog. I create a new bus and call it e.g. "FluidSynth". Bus settings "FluidSynth" -> "Master". I do not add any midi events. Switching between the options in the drop down lists of "input bus" and "output bus" several times (FluidSynth -> FluidSynth, Master -> FluidSynth, Master -> Master, ...) makes Qtractor crash :-( even without loading any lv2-plugins which was my first suspect. Qtractor is not in play modus.

Changing the desktop theme didn't help either (gtk suspected issue).

The terminal always reports "memory access error". I don't think it's a hardware defect, becaus e.g. Ardour and Rosegarden perform stable in the same system.

Greetings, Michael

rncbc's picture

Switching between the options in the drop down lists of "input bus" and "output bus" several times (...) makes Qtractor crash :-(

so it sounds like an ugly old heisenbug is back :S

I'll keep trying to first reproduce those crashes--with i still fail to miserably--and delve into it as much as this global lockdown permits ;)

stay safe

babarosa's picture

Very strange, with today's version "qtractor-" this heisenbug seems to be gone. Heavily I switched busses until the mouse pointer was destroyed, though no crash. I really don't know what was going on and feel sheepish once again.

Thank you for your efforts! Greetings, Michael

rncbc's picture

hi Michael, no worries, that's what heisenbugs do :)

stay safe and your meaningful-others too
keep on rocking in a locked-down world ;)

The Traveler's picture

Greetings to all,
Just joined the forum but wanted to confirm that qtractor from the ppa solved the crash for me as well. I had been using the AppImage from the website and had the same issues as the OP. Using the ppa version solved it and I haven't found any other issues currently. I run on a self-customized ubuntu server install with lxqt-core desktop layered on top with i5-8600K 3,4Ghz and 32M of 2666 DDR4 RAM. I've stripped out pulseaudio and run jackd2 and alsa. Stability heaven. :)

Cheers and stay well.

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