Am 21.12.2016 8:10 vorm. schrieb "Alexandre Bergel" <alexandre.bergel@me.com>:
I had plenty of elements in my Roassal visualization, and on some point it just crashed.
I have the impression that having many elements and / or animations (as in the case of Johan Fabry) triggers the crash.


One problem, the one peter (partly) fixed, is n issue with bitblt, Cairo (as a surface plugin) and garbage collection.
Bitblt my call the surface plugin to request some information about the Form.
NB-based ffi for Cairo just called gen. asm code. But with UFFI, we now callback to Smalltalk code, which may trigger a GC.
So every time bitblt, makes a call to the surface plugin (Cairo) and this callback allocates a new ST-Object, the GC may run and moves(!)the objects, to which bitblt still holds a reference.
Accessing this objects in bitblt, after the callback returns (may) result in a segfault.
Depending on the concrete bltoperation, the object memory layout, the size(!) of the initial Cairo surface.��
With peters fix/hack, the code does not crash but it still may access and operates on moved objects.
Pining the objects may help, but you need to know where in the (vm image) code a form is used for drawing, and if it is a real form or external data managed by the surface plugin.
And of course, when to "unpin" the object.

A saver way would be, to just disable any GC during the executing of the callback, if it was called by a plugin (here:bitblt)



Alexandre


> On Dec 20, 2016, at 9:12 AM, Stephane Ducasse <stepharo.self@gmail.com> wrote:
>
> So what was your crash problem?
>
>
> On Tue, Dec 20, 2016 at 8:43 AM, Alexandre Bergel <alexandre.bergel@me.com> wrote:
> > so did it work?
> > Is there something that we should do?
>
> I had no problem, but as Henrik and Peter said, the problem is likely to be more complex
>
> Alexandre
>
>
> >
> > On Fri, Dec 16, 2016 at 5:06 PM, Alexandre Bergel <alexandre.bergel@me.com> wrote:
> > Okay, trying���
> >
> > Alexandre
> >
> >
> > > On Dec 16, 2016, at 4:40 PM, Aliaksei Syrel <alex.syrel@gmail.com> wrote:
> > >
> > > According to crash.dmp TRMorph>drawOn: draws an image using FormCanvas>>#image:at:sourceRect:rule:�� at a coordinate represented by a Float point.
> > > Try to round it to integer point.
> > >
> > > Cheers,
> > > Alex
> > >
> > > On 16 December 2016 at 16:34, Alexandre Bergel <alexandre.bergel@me.com> wrote:
> > > Hi!
> > >
> > > Vincent and I are experiencing many crashes from GrafPort>copyBits. It crashes every couple of minutes.
> > >
> > > I know that not much can be done so far. Stability is my biggest concern with Pharo :-(
> > > I use the latest VM.
> > >
> > > Cheers,
> > > Alexandre
> > >
> > >
> > >
> > >
> > >
> > >
> > > --
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--
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Alexandre Bergel�� http://www.bergel.eu
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