[vtk-developers] InvokeEvent test randomly failing quiz

[Utkarsh Ayachit]

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]
>
>
>
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