MantisBT - VTK
at method: void vtkFixedPointVolumeRayCastMapperComputeCS1CGradients(...)
This method deliberately calls the
me->InvokeEvent( vtkCommand::VolumeMapperComputeGradientsStartEvent, NULL );
me->InvokeEvent( vtkCommand::VolumeMapperComputeGradientsEndEvent, NULL );
methods to inform the application layer that the events
VolumeMapperComputeGradientsStartEvent
VolumeMapperComputeGradientsEndEvent
are about to happen.
However the vtkFixedPointVolumeRayCastMapperComputeCS1CGradients method is designed to be run on multiple threads/processor but it uses the vtkSubjectHelper::InvokeEvent method which is not thread safe.
In our case VTK created 3 threads for gradient computation.
During the computation and during the above InvokeEvent calls the vtkObjectBase::ReferenceCount member was compromised inside the our subclassed vtkCommand instance.
This means that the reference count decreased to 0 and the vtkCommand deleted while there were still references for it.
After a while the framework dereferenced that deleted class --> it lead to crash
Solution:
=========
VTK 5.2.0 as been patched in order to avoid the InvokeEvent from multiple threads. The patch consist of calling the InvokeEvent methods right before thread creation (vtkCommand::VolumeMapperComputeGradientsStartEvent) and right after the thread exit (vtkCommand::VolumeMapperComputeGradientsEndEvent)
These takes place at file
vtkFixedPointVolumeRayCastMapper.cxx
at method
vtkFixedPointVolumeRayCastMapper::ComputeGradients
Note:
=====
The other call for
me->InvokeEvent( vtkCommand::VolumeMapperComputeGradientsProgressEvent, args );
has succeeded without such a problem because it was fired in case of:
thread_id == 0
which was on purpose, I presume.
- HP xw8400 Workstation (4x3.0GHz Xeon CPU, 4GB RAM, 2x150MB image disk)
- Linux version 2.6.15-2.5 (root@alfred) (gcc version 4.0.2 20051125 (Red Hat 4.0.2-8)) #1 SMP PREEMPT Tue Sep 19 10:56:25 CDT 2006
original-vtkFixedPointVolumeRayCastMapper.cxx (120,079) 2009-02-23 07:58https://www.vtk.org/Bug/file/7072/original-vtkFixedPointVolumeRayCastMapper.cxx
patched-vtkFixedPointVolumeRayCastMapper.cxx (123,007) 2009-02-23 07:58https://www.vtk.org/Bug/file/7073/patched-vtkFixedPointVolumeRayCastMapper.cxx