[vtkusers] AWT + SWT + Event Loops (was Re: VTK6 and Java Cone Example 5)

rkwright rkwright at geofx.com
Wed Aug 14 11:53:02 EDT 2013 

Seb,

Yes, the crash is the same. Sometimes it isn't even at close time - the app
will hang then crash.  When I have been able to pause inside and look or get
a look at the stack it is buried way down in SWT or some inner message loop
in VTK.  I strongly suspect that it is some threading issue between VTK and
SWT.  You mentioned that VTK is not thread­safe while Eclipse and SWT use
LOTS of threads.  Like you say, if you stick with VTK alone (in ObjectiveC
and/or C++) it is fine.

So if I want to write in Java and use Eclipse I a few choices:
* Give up on using Java and Eclipse, just use Xcode and Objective C/C++
* Carefully use VTK, avoiding any danger spots (e.g. Interactors) but I
won't know what to avoid until I get there
* Abandon trying to use VTK and go back to my VTK equivalent which is far
more primitive.
My problem is that I don't want to fight the tools.  I don¹t WANT to write
rendering systems, etc.  Been there, done that (I've written parts 2
PostScript interpreters, was part of the SVG Viewer team at Adobe,
Illustrator, etc.).  I'm looking for a system I can just use and not have to
fix or work around.  It may be that the message is stop fighting and accept
using Xcode.  Is that what you work in?  Xcode and Objective C/C++?

Thanks
Ric


From:  "Sebastien Jourdain-2 [via VTK]"
<ml-node+s1045678n5722739h47 at n5.nabble.com>
Date:  Wednesday, August 14, 2013 10:41 AM
To:  Ric Wright <rkwright at geofx.com>
Subject:  Re: AWT + SWT + Event Loops (was Re: VTK6 and Java Cone Example 5)

Hi Ric,

I have no experience with SWT, so I can't really help you here, but I can
ensure you that VTK works just fine on Mac OS X with Java 6 and interaction.
In fact, I never had any crash at close time.

Does the sample code from the vtk.jar crash in the same manner at close time
?

Seb


On Wed, Aug 14, 2013 at 11:08 AM, rkwright <[hidden email]
</user/SendEmail.jtp?type=node&node=5722739&i=0> > wrote:
> Sebastien,
> 
> (BTW, thank you very much for your patience in answering my questions in such
> timely fashion).
> 
> I didn't see the SWT option when I built VTK the first time.  However, I took
> a break and quickly built an Eclipse plugin using the code in
> wrapping/java/vtk/rendering.  I created a view based on the
> swtConeRenderer.java code, substituting the parent SWT composite passed to the
> ViewPart creation step, passing that composite to the constructor of
> vtkSwtComponent.  It ALMOST works except that it creates a wholly new window
> outside the actual Eclipse view.  And that view works, complete with
> mouse-wheel scaling.  BUT, when I close that view Š  it crashes Eclipse,
> exactly as it does in the other demo I put together using the SWT_AWT bridge.
> Same message, same crash in Eclipse.  Clearly, something goes horribly awry
> down in the bowels of the native code in SWT.
> 
> So I will continue to experiment with VTK but avoid anything to do with
> interactors.  But I return to my earlier question: Am I likely to run into
> similar problems or is it largely or wholly in the interactors that VTK
> starts/handles its own event loops?  So far the only problems I have seen are
> when interactors are involved (though my experience is rather limited, of
> course).
> 
> Thanks
> Ric
> 
> 
> From:  "Sebastien Jourdain-2 [via VTK]" <[hidden email]
> <http://user/SendEmail.jtp?type=node&node=5722738&i=0> >
> Date:  Wednesday, August 14, 2013 9:53 AM
> 
> To:  Ric Wright <[hidden email]
> <http://user/SendEmail.jtp?type=node&node=5722738&i=1> >
> Subject:  Re: AWT + SWT + Event Loops (was Re: VTK6 and Java Cone Example 5)
> 
> You need to build VTK with the SWT component ON. Moreover,
> vtkRenderWIndowInteractor does not spawn a new event loop as VTK is NOT thread
> safe.
> 
> 
> On Wed, Aug 14, 2013 at 10:31 AM, rkwright <[hidden email]
> <http://user/SendEmail.jtp?type=node&node=5722733&i=0> > wrote:
>> I have been working through the samples in the jar. The only failure so far
>> is the vtkRenderWindowInteractor.
>> 
>> I was not aware of a SWT component in VTK.  I see a Java file
>> vtkSwtComponent.java but it isn't clear to me that it is going to solve my
>> problems.   There are two issues I see:
>> * vtkSwtComponent appears to use the SWT OpenGL canvas widget.  This is
>> largely unsupported in SWT and was half-broken last time I looked at it.  I
>> gave up on it long ago and turned to JOGL embedding in SWT via the bridge
>> (which works for me at present)
>> * It's not clear how this would solve the other issue where
>> vtkRenderWIndowInteractor spawns its own event loop and that causes problems
>> with SWT ­ or does vtkRenderWIndowInteractor not use any AWT utilities or
>> methods?
>> I'll experiment with the vtkSwtComponent (I see one simple example file,
>> swtConeRendering.java) and see if that helps. Though there is no SWT support
>> in vtk.jar so I'll guess I'll have to include the SWT files directly in my
>> project.
>> 
>> Thanks for your advice.
>> 
>> Ric
>> 
>> BTW, I am running Apple's Java 1.6.0_51-b11-457-11M4509. 64 bit
>> 
>> From:  "Sebastien Jourdain-2 [via VTK]" <[hidden email]
>> <http://user/SendEmail.jtp?type=node&node=5722724&i=0> >
>> Date:  Wednesday, August 14, 2013 8:42 AM
>> To:  Ric Wright <[hidden email]
>> <http://user/SendEmail.jtp?type=node&node=5722724&i=1> >
>> Subject:  Re: AWT + SWT + Event Loops (was Re: VTK6 and Java Cone Example 5)
>> 
>> Just read the sample codes that are provided in the vtk.jar or in the Source
>> code under Wrapping/Java/vtk/sample, they should be pretty strait forward.
>> Moreover, VTK do provide a SWT component for rendering if you build it, so
>> you shouldn't have any event loop issue...
>> 
>> Seb
>> 
>> 
>> On Wed, Aug 14, 2013 at 9:30 AM, Ric Wright <[hidden email]
>> <http://user/SendEmail.jtp?type=node&node=5722710&i=0> > wrote:
>>> So did some more spelunking and it looks like this is just a basic
>>> incompatibility for SWT and AWT ­ in the specific case where AWT is trying
>>> to start their own event loop once SWT has started.  Previously, in my other
>>> work, I handled events on my own ­ I didn't ask or expect AWT to start or
>>> manage it's own events. I used AWT basically to host the OpenGL canvas
>>> (based on JOGL).  But when one invokes the vtkRenderWIndowInteractor an
>>> event loop IS spawned and the causes various weird problems.
>>> 
>>> There is a fairly long summary of some of the issues here:
>>> 
>>> http://marc.info/?l=openjdk-awt-dev&m=135818602009136&w=2
>>> 
>>> So the question that comes to my mind is how dependent is the rest of VTK on
>>> starting its own event loops?  I.e. Can I use the rest of VTK and its
>>> pipeline to perform graphics, manage datasets, etc.  I am willing to give up
>>> the Interactor and its mimicking of trackball if everything else is likely
>>> to work.  But if spawning its own event loop(s) is intrinsic to how most of
>>> VTK works then I'm probably dead in the water.
>>> 
>>> Thoughts or suggestions?
>>> 
>>> Thanks
>>> Ric
>>> 
>>> 
>>> From:  Ric Wright <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=1> >
>>> 
>>> Date:  Tuesday, August 13, 2013 12:59 PM
>>> To:  Sebastien Jourdain <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=2> >
>>> Cc:  Sean McBride <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=3> >, vtkusers <[hidden
>>> email] <http://user/SendEmail.jtp?type=node&node=5722710&i=4> >
>>> 
>>> Subject:  Re: [vtkusers] VTK6 and Java Cone Example 5
>>> 
>>> An update on this.  I ported over some of my other Eclipse work and adapted
>>> it to VTK.  It is pushed to my account on github and there is a writeup
>>> here:  http://rkwright.github.io/geofx-pages/vtkview.html.  There are 3
>>> articles in there.  The latest rev of the code is here:
>>> https://github.com/rkwright/vtkscene in the develop branch.
>>> 
>>> Mostly, it works great.  However, when I tried the fifth cone example, which
>>> has the problematic vtkRenderWindowInteractor, I ran into similar problems
>>> as before.  I instantiated it with a valid vtkPanel.RenderWindow but it
>>> still goes off into the ozone, sometimes crashing the native vtkOpenGL
>>> dylib.
>>> 
>>> I'm going to skip the interactor for now and move on to see if I run into
>>> more problems. If not, I can probably live without that widget but the
>>> problems there might be symptomatic of deeper problems on OSX 64 bit
>>> systems.
>>> 
>>> Any further suggestions would be welcome.
>>> 
>>> Thanks
>>> Ric
>>> 
>>> 
>>> From:  Sebastien Jourdain <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=5> >
>>> 
>>> Date:  Tuesday, August 6, 2013 8:56 AM
>>> To:  Ric Wright <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=6> >
>>> Cc:  Sean McBride <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=7> >, vtkusers <[hidden
>>> email] <http://user/SendEmail.jtp?type=node&node=5722710&i=8> >
>>> 
>>> Subject:  Re: [vtkusers] VTK6 and Java Cone Example 5
>>> 
>>> In Java you should use the Java specific classes anyway like
>>> vtkPanel/vtkCanvas or the new version of them used in the vtk.sample package
>>> of the vtk.jar...
>>> 
>>> The purpose of those example was to show the possible match between the
>>> different languages...
>>> 
>>> Nothing more I believe,
>>> 
>>> Seb
>>> 
>>> 
>>> On Tue, Aug 6, 2013 at 8:52 AM, Ric Wright <[hidden email]
>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=9> > wrote:
>>>> Ah, OK.  Well, I don't know what to do here.  Is this happening to others?
>>>>  Should I file a bug?  Just try to work around it by not using
>>>> RenderWindowInteractors (sounds kind of lame).  Or?
>>>> 
>>>> Suggestions?
>>>> 
>>>> Thanks
>>>> Ric
>>>> 
>>>> 
>>>> On 8/5/13 4:15 PM, "Sean McBride" <[hidden email]
>>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=10> > wrote:
>>>> 
>>>>> >On Mon, 5 Aug 2013 16:10:55 -0500, Ric Wright said:
>>>>> >
>>>>>> >>Well, a little playing around didn't seem to help, but I am frankly not
>>>>>> >>an
>>>>>> >>expert on threads.  However, it seems to me that the source of the
>>>>>> >>problem
>>>>>> >>is that the vtkRenderWindowInteractor gets initialized then the start()
>>>>>> >>method creates an event loop that is monitored by the
>>>>>> >>vtkRenderWindowInteractor.  I suspect that start() method spawns a new
>>>>>> >>thread to listen to the events and it is the spawning of that thread
>>>>>> that
>>>>>> >>causes the exception.
>>>>> >
>>>>> >VTK's Cocoa classes never create any threads.
>>>>> >
>>>>> >Cheers,
>>>>> >
>>>>> >--
>>>>> >____________________________________________________________
>>>>> >Sean McBride, B. Eng                 [hidden email]
>>>>> <http://user/SendEmail.jtp?type=node&node=5722710&i=11>
>>>> 
>>>>> >Rogue Research                        www.rogue-research.com
>>>>> <http://www.rogue-research.com>
>>>>> >Mac Software Developer              Montréal, Québec, Canada
>>>>> >
>>>>> >
>>>> 
>>>> 
>>> 
>> 
>> 
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