[Interest] [Qt3D] Logic aspect hangs on exit

[Sean Harmer]

On Thursday 17 Dec 2015 12:17:48 Nye wrote:
> Hello Harald,
> In fact this is what I'm attempting, but realized that there is a more
> "subtle" way to do it. I think that switching the root entity and/or the
> frame graph would be more appropriate, than to actually create two separate
> GL widgets/windows.
> 
> Sean,
> No I don't really have any specific use cases. I think how it's now is
> fine. I believe my code hangs because of the order of destruction of my
> widgets, coupled with me creating the aspect engine on the stack. The
> actual dead-lock I get in qaspectmanager.cpp @ 246 : m_waitForEndOfExecLoop.
> acquire(1);
> My guess is for some reason, because of the structure of my objects, the
> event loop is not exiting. Still I wasn't able to reproduce it in a clean
> separate projects, so I'll continue debugging and if necessary will file a
> bug report.

Hmm, I wonder if this regression is a side effect of another fairly recent fix 
made to avoid a data race with dynamically updated buffers and VAOs in the 
renderer. I'll dig into it. Thanks for the info.

Sean

> 
> Kind regards.
> 
> On Thu, Dec 17, 2015 at 12:08 PM, Harald Vistnes <harald.vistnes at gmail.com>
> 
> wrote:
> > Hi,
> > 
> > I'm also interested in how to handle multiple windows with Qt3D. My use
> > case is a widgets based CAD like application that will have two
> > independent
> > 3D windows in a QStackedWidget (so only one 3D window will be visible at a
> > time). They will have different models loaded and the user will switch
> > from
> > one window to the other. Also, for each window, it must be possible to
> > render the current view (root QEntity) to a high-res image.So in this case
> > I guess there will be one QAspectEngine for each of the windows and then
> > temporary QAspectEngines for offscreen rendering that shares the root
> > entity with the other QAspectEngines?
> > 
> > Harald
> > 
> > 2015-12-17 10:49 GMT+01:00 Sean Harmer <sean.harmer at kdab.com>:
> >> On Thursday 17 Dec 2015 11:37:49 Nye wrote:
> >> > Hello,
> >> > It (most probably) is a problem with my code. I've created two aspect
> >> > engines (this is in a widget and I have two instances). I suppose
> >> > having
> >> > two aspect engines is not allowed? I've done it this way, because the
> >> > aspect engine handles a single surface/window. Interestingly, it
> >> > happens
> >> > only with the logic aspect. On a related note, what would be the proper
> >> 
> >> way
> >> 
> >> > to use two gl windows with Qt3D?
> >> 
> >> At present it is indeed to make two QAspectEngines as you are doing. This
> >> is
> >> something I'm looking into at the moment as it happens - well more
> >> generally
> >> what top level integration points do we need to support for the initial
> >> version.
> >> 
> >> If you have specific use cases, I'd be interested to hear what they are.
> >> 
> >> Cheers,
> >> 
> >> Sean
> >> 
> >> > Kind regards.
> >> > 
> >> > On Thu, Dec 17, 2015 at 10:52 AM, Sean Harmer <sean.harmer at kdab.com>
> >> 
> >> wrote:
> >> > > Hi,
> >> > > 
> >> > > Can you file a bugreport with a small test case for this please? This
> >> 
> >> was
> >> 
> >> > > certainly working in the cases I tested. Perhaps there's a regression
> >> 
> >> we
> >> 
> >> > > need
> >> > > to fix.
> >> > > 
> >> > > Thanks,
> >> > > 
> >> > > Sean
> >> > > 
> >> > > On Thursday 17 Dec 2015 09:51:51 Nye wrote:
> >> > > > Hello,
> >> > > > It seems for some reason that adding a logic aspect to the aspect
> >> 
> >> engine
> >> 
> >> > > > causes the application to "hang" on exit. My guess is that for some
> >> > > 
> >> > > reason
> >> > > 
> >> > > > the shutdown sequence is not executing properly and the threads in
> >> 
> >> the
> >> 
> >> > > pool
> >> > > 
> >> > > > are left in waiting. Is there currently a workaround for that (i.e.
> >> 
> >> can
> >> 
> >> > > > I
> >> > > > manually shutdown the aspect engine)? I'm creating the aspect
> >> 
> >> engine on
> >> 
> >> > > the
> >> > > 
> >> > > > stack, maybe this is an issue?
> >> > > > I'm developing on Debian stretch with 4.2 kernel, if that helps.
> >> 
> >> Qt3D is
> >> 
> >> > > > compiled from the most recent source available in the git
> >> 
> >> repository for
> >> 
> >> > > > the 5.6 branch.
> >> > > > 
> >> > > > Kind regards.
> >> > > 
> >> > > --
> >> > > Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> >> > > KDAB (UK) Ltd, a KDAB Group company
> >> > > Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
> >> > > Mobile: +44 (0)7545 140604
> >> > > KDAB - Qt Experts
> >> 
> >> --
> >> Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> >> KDAB (UK) Ltd, a KDAB Group company
> >> Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
> >> Mobile: +44 (0)7545 140604
> >> KDAB - Qt Experts
> >> _______________________________________________
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-- 
Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
KDAB (UK) Ltd, a KDAB Group company
Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
Mobile: +44 (0)7545 140604
KDAB - Qt Experts