Freeze on nested eventloops (QFileDialog::getOpen*)

[Andreas Hartmetz]

On Monday 22 June 2015 01:09:59 Boudhayan Gupta wrote:
> Hi,
> 
> If you're talking about the static QFileDialog::getOpen* methods, I
> may have hit a similar issue with the static QFileDialog::getSaveFile*
> methods. I was working on KScreenGenie, and the app just crashed
> maybe one out of every three or four times the Save File dialog
> opened. Not a lockup, but an outright crash.
> 
> At that point I thought I was making an error on my part, so I just
> ended up manually creating a QFileDialog and working with it. Just
> reporting this, in case it's related.
> 
> -- Boudhayan Gupta
> 

Hello!

You have something valuable on your hands, a way to reproduce the 
problem that will dump you into a debugger (usually) close to the 
location where the bug is happening. If you could take a backtrace of 
the crash, that could get us to a solution more quickly. It seems like 
an important bug.

(formal stuff)
While the kind of your message is suitable for top-posting on its own, I 
suggest that you still keep bottom-posting on a technical mailing list 
such as this. At some point, it's going to get into technical details 
again and then it's good to have everything in chronological / topical 
order top to bottom.

> On 21 June 2015 at 20:29, Andreas Hartmetz <ahartmetz at gmail.com> 
wrote:
> > On Sunday 14 June 2015 15:00:57 Milian Wolff wrote:
> >> Hey all,
> >> 
> >> in massif-visualizer's framework branch, and now also kate, I
> >> sometimes notice GUI lockups when I try to open files via Ctrl + O.
> >> The backtraces look like the following:
> >> 
> >> https://paste.kde.org/pbzhkgx8r
> >> 
> >> Any idea what might be going on here? Is it not a good idea to mix
> >> system compiled KF5-based stuff (e.g. KDEPlatformTheme.so) with
> >> kdesrc-build compiled KF5 libraries (/home/milian/projects/kf5/*)?
> >> 
> >> The applications do not recover from this lockup.
> > 
> > I recently got the apparently same hang in Kate twice in one day.
> > The
> > application froze while IIRC not using CPU cycles and didn't
> > recover. I did not attach gdb. To the best of my knowledge,
> > everything from qtbase up (5.5 branch) is self compiled so there is
> > no mixing with distro provided libraries.
> > I have checked "info shared" in gdb and found nothing Qt related
> > coming from /usr. This is now a few days after the hangs so there
> > is a small probability that something changed.