[vtk-developers] InvokeEvent test randomly failing quiz

[David Gobbi]

It looks like the fix didn't work.  But now that I know which dashboard is
failing, and have seen the whole stack trace, I have a better idea of where
the problem might be.  I'll give it another shot tonight.

 - David

On Tue, Nov 1, 2016 at 11:48 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> I wasn't able to reproduce the issue, but I think that I found out what
> causes it.  When vtkPythonCommand::Execute() is called, it tries to promote
> the subject object (i.e. the object being deleted for DeleteEvent) into a
> Python object.  I was able to confirm that this actually happens, and even
> though I couldn't get it to crash, I'm pretty sure that it puts the program
> into a bad state.
>
> See https://gitlab.kitware.com/vtk/vtk/merge_requests/2131
>
>  - David
>
> On Tue, Nov 1, 2016 at 9:19 AM, Utkarsh Ayachit <
> utkarsh.ayachit at kitware.com> wrote:
>
>> Ken,
>>
>> The issue seems to be that the callback is attempted to be called for
>> vtkCommand::DeleteEvent since the observer is set to respond to
>> "AnyEvent".  When the object is being cleaned up as part of the
>> interpreter being destroyed, calling Python commands is indeed
>> problematic and hence the failure.
>>
>> The test can be fixed by changing the observer to only listen to
>> ModifiedEvent instead of AnyEvent. Ideally vtkPythonCommand::Execute
>> can check if the interpreter is being cleaned up, but I am not sure
>> how to do that.
>>
>> Utkarsh
>>
>> On Tue, Nov 1, 2016 at 10:33 AM, Ken Martin <ken.martin at kitware.com>
>> wrote:
>> > OK here is a puzzle. We have a test that is occasionally failing and I
>> > suspect it fails due to random python order of deletion of vtk objects.
>> The
>> > relevant python code is below. It fails when unregistering a vtkObject
>> and I
>> > suspect it is failing when invoking an callback during the
>> > unregisterinternal method see the stack trace. So maybe python has
>> deleted
>> > the object from its maps but then it gets used in a callback for another
>> > object being deleted? Again my python foo is weak but maybe we have to
>> > unregister the anyEvent observer before the end of the script? Maybe
>> > something else?
>> >
>> >     @vtk.calldata_type(vtk.VTK_OBJECT)
>> >     def callbackObj(self, caller, event, calldata):
>> >         self.calldata = calldata
>> >
>> >     def setUp(self):
>> >         self.vtkObj = vtk.vtkObject()
>> >
>> >         self.vtkObjForCallData = vtk.vtkObject()
>> >
>> >     def test_obj(self):
>> >         self.vtkObj.AddObserver(vtk.vtkCommand.AnyEvent,
>> self.callbackObj)
>> >         self.vtkObj.InvokeEvent(vtk.vtkCommand.ModifiedEvent,
>> > self.vtkObjForCallData)
>> >         self.assertEqual(self.calldata, self.vtkObjForCallData)
>> >
>> > 0x7f98bd3e8770 : ??? [(???) ???:-1]
>> > 0x7f98bd19b778 : vtkPythonCommand::Execute(vtkObject*, unsigned long,
>> void*)
>> > [(libvtkWrappingPython35Core-7.1.so.1) ???:-1]
>> > 0x7f98bcb9fd7e : ??? [(???) ???:-1]
>> > 0x7f98bcba000c : vtkObject::UnRegisterInternal(vtkObjectBase*, int)
>> > [(libvtkCommonCore-7.1.so.1) ???:-1]
>> > 0x7f98bd19f045 : vtkPythonUtil::RemoveObjectFromMap(_object*)
>> > [(libvtkWrappingPython35Core-7.1.so.1) ???:-1]
>> > 0x7f98bd1a5b30 : PyVTKObject_Delete [(libvtkWrappingPython35Core-7
>> .1.so.1)
>> > ???:-1]
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtk-developers/attachments/20161102/5005d25b/attachment.html>