Re: Help with debugging a bug in Konqueror

El dilluns, 13 de juliol del 2026, a les 9:39:58 (Hora d=E2=80=99estiu d=E2=
=80=99Europa=20
central), Stefano Crocco va escriure:
> On luned=C3=AC 13 luglio 2026 08:49:46 Ora legale dell=E2=80=99Europa cen=
trale you wrote:
> > On Mon, 2026-07-13 at 08:41 +0200, Stefano Crocco wrote:
> > > Hello to everyone,
> > > for the last few weeks, I've randomly encountered what I assume is a
> > > bug in
> > > Konqueror: I'd like to fix it, because it's rather annoying, but I
> > > don't know
> > > how to debug it to find its cause.
> > >=20
> > > The issue is that sometimes Konqueror completely freezes: none of its
> > > windows
> > > respond to mouse or keyboard. The only way to go on is to kill it.
> > > It's not a
> > > frequent issue: it usually happens once a day or so. Once it has
> > > happened,
> > > however, it's likely to happen again in a short time.
> > >=20
> > > I attach a backtrace by attaching gdb to the Konqueror instance once
> > > the
> > > freeze happens. As you can see, it contains almost nothing from
> > > Konqueror
> > > itself: just two calls near the bottom, the last of which is a call
> > > to
> > > QApplication::exec(). All other function calls are either inside KDE
> > > Frameworks or Qt: I'd almost think this is not a problem with
> > > Konqueror if it
> > > were not for the fact that I'm only experiencing the issue with
> > > Konqueror.
> >=20
> > Are you sure freeze happens in that thread?
> >=20
> > The stacktrace is from the rendering thread. Does Konqueror window get
> > "grayed out" by KWin when it freezes? If it doesn't I'd think the
> > freeze happens in another thread.
>=20
> Thanks for the answer. No, the Konqueror  window doesn't look grayed out:=
 it
> looks completely normal to the point that often I don't realize it has
> frozen until I try to interact with: only at that point I notice that all
> parts of the UI don't respond in any way yo mouse or keyboard. If I
> minimize the window, then restore it, its contents aren't drawn so that it
> shows the contents of the previously active window.
>=20
> > > Given the randomness of the freezes and the fact that the backtrace
> > > contains
> > > almost no Konqueror-specific calls, I really have no ideas on how to
> > > proceed to
> > > debug the issue, and I really don't even know what to search on the
> > > web. Do
> > > you have any advice?
> > >=20
> > > Thanks in advance
> > >=20
> > > Stefano
>=20
> I attach a new backtrace with all threads (compressed because of size). I
> still can't see anything related to Konqueror. The only thing I can notice
> is a mention of QDBus in thread 67, but I still don't know what informati=
on
> to get from it. Any other ideas?

Does it always get stuck in glXSwapBuffers ?

That would call for a driver bug possibly?

Does using

export QT_XCB_FORCE_SOFTWARE_OPENGL=3D1

make it not get stuck?

Cheers,
  Albert

>=20
> Thanks
>=20
> Stefano