For slicer 4.1 release I made this change:

http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=19676

Ron, let me know if you ever see this issue again.

For future use test should replicate the issue:

https://github.com/pieper/Slicer/blob/9a5ef6bdf2b95946553111ea0265102d04cda067/Modules/Scripted/EditorLib/Testing/ThresholdThreadingTest.py

it requires some changes in various parts of the code so I will commit it to the trunk after the 4.1 code freeze is over.

Ron showed me what may be a issue that arose in the ChangeLabelEffect being used to remove the background label from a growcut result.

This is implemented with this class:

class VTK_SLICER_BASE_LOGIC_EXPORT vtkImageLabelChange : public vtkImageToImageFilter

Is there an action item for me on this?

In the HelperBox code, it is written that the multi-threaded version of 'vtkImageThreshold' should not be used until 0001822 (this issue) is solved and this issue mention that the commit adding the same message is resolving the issue ...

... this looks like a "catch 22". Should we update the comment in the code to mention that the multi threading is disabled for some unknown/To-Be-Determined reason and that for more details, developer should refer to issue 1822 ?

May be the underlying issue is addressed by this commit: https://github.com/Kitware/VTK/commit/242656448e ?

I don't think the commit Jc referenced is related - the split operation uses a regular threshold operation and the extents are not different between input and output.

Steve, could you please test if the issue is still there on Mac with current vtk7 version? There is a test that you created that you can run to reproduce the problem.

I tested this on today's Nightly (with vtk7) and I couldn't replicate the issue (good!). I'll go ahead and remove the line that forces single threading[1] and check in the result.

https://github.com/Slicer/Slicer/blob/846a654748e263ca51ac43c0d324d260c03e008e/Modules/Scripted/EditorLib/EditUtil.py#L345