segfault in rendergraph

[ronso0]

Bug Description

While trying to reproduce #14359 with that example track I got the following segfault

• start Mixxx
• load track via double-click
• click into middle of saved loop in the overview
• click a hotcue button (would cause a seek and preview)
• segfault

Couldn't reproduce again unfortunately.

Thread 1 "mixxx" received signal SIGSEGV, Segmentation fault.

0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in  ()
#1  0x00005555568ca8e8 in rendergraph_gl::Engine::render(rendergraph_gl::BaseNode*) (pNode=0x55557274ca30, this=<optimized out>) at /src/master/src/rendergraph/opengl/engine.cpp:62
#2  rendergraph_gl::Engine::render(rendergraph_gl::BaseNode*) (pNode=0x555567e43a00, this=<optimized out>) at /src/master/src/rendergraph/opengl/engine.cpp:63
#3  rendergraph_gl::Engine::render(rendergraph_gl::BaseNode*) (this=0x5555717628d0, pNode=0x55556a81e0f8) at /src/master/src/rendergraph/opengl/engine.cpp:63
#4  0x00005555568cab26 in rendergraph_gl::Engine::render(rendergraph_gl::BaseNode*) (pNode=0x555567e88120, this=0x5555717628d0) at /src/master/src/rendergraph/opengl/engine.cpp:63
#5  rendergraph_gl::Engine::render() (this=0x5555717628d0) at /src/master/src/rendergraph/opengl/engine.cpp:54
#6  0x0000555556655dc9 in non-virtual thunk to allshader::WaveformWidget::render() () at /src/master/src/waveform/widgets/allshader/waveformwidget.h:33
#7  0x00005555564d151d in WaveformWidgetFactory::renderSelf() (this=this@entry=0x555564934470) at /src/master/src/waveform/waveformwidgetfactory.cpp:758
#8  0x00005555564d171d in WaveformWidgetFactory::render() (this=0x555564934470) at /src/master/src/waveform/waveformwidgetfactory.cpp:793
#9  0x00007ffff2616c1b in QObject::event(QEvent*) () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#10 0x00007ffff67cafb6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt6Widgets.so.6
#11 0x00007ffff67d5410 in QApplication::notify(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt6Widgets.so.6
#12 0x000055555614f783 in MixxxApplication::notify(QObject*, QEvent*) (this=0x7fffffffd900, pTarget=0x555564934470, pEvent=0x7fff140045e0) at /src/master/src/mixxxapplication.cpp:207
#13 0x00007ffff25c9830 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#14 0x00007ffff25cd02c in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#15 0x00007ffff2807c67 in  () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#16 0x00007ffff592b17d in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007ffff592b400 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#18 0x00007ffff592b4a3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#19 0x00007ffff2807708 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#20 0x00007ffff25d5eeb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#21 0x00007ffff25d1d13 in QCoreApplication::exec() () at /lib/x86_64-linux-gnu/libQt6Core.so.6
#22 0x00005555559c73ef in (anonymous namespace)::runMixxx (args=<optimized out>, pApp=0x7fffffffd900) at /src/master/src/main.cpp:108
#23 main(int, char**) (argc=<optimized out>, argv=0x7fffffffdbc8) at /src/master/src/main.cpp:243

Version

main 2.6-alpha fef7062

OS

No response

[acolombier]

Sounds like a potential race condition? I'll try and have a look if I can
CC @m0dB who might know how to fix/prevent as well!