[Interest] Odd crash with QPainter + QOpenGLWidget

Jérôme Godbout godboutj at amotus.ca
Thu Mar 28 14:58:42 CET 2019

For my usage that will be enough, most of them use Ubuntu/gentoo. If they use something exotic, I will have to check with them and they will need to run it into a VM to have issue with this. I will create a fallback if ever needed ( a fraction of a fraction of a fraction of 1% ain't time worthy sadly).

-----Original Message-----
From: Interest <interest-bounces at qt-project.org> On Behalf Of Thiago Macieira
Sent: March 27, 2019 9:05 PM
To: interest at qt-project.org
Subject: Re: [Interest] Odd crash with QPainter + QOpenGLWidget

On Wednesday, 27 March 2019 14:48:16 PDT Matthew Woehlke wrote:
> ==12997==    by 0x598A728: QOpenGLVertexArrayObjectPrivate::destroy()
> (qopenglvertexarrayobject.cpp:212)
> ==12997==  Address 0x8 is not stack'd, malloc'd or (recently) free'd

Line 212:

        if (QThread::currentThread() != qGuiApp->thread()) {

There is a pointer being dereferenced on that line: qGuiApp, which is:

#define qGuiApp (static_cast<QGuiApplication *>(QCoreApplication::instance()))

That means you're somehow running this code after the application object was destroyed. Your backtrace wasn't long enough to tell where this was being called from (run valgrind with --num-callers=20), but my guess is that it's a global destructor keyed to the font engine.

But I also don't see how this could be *your* fault. If you can get the full backtrace, I think you should report as a bug.
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel System Software Products

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