[vtkusers] vtkImageAppend does not work correctly with multiple threads

[Dominik Szczerba]

Hi David,

I submitted a bug with example data and steps to reproduce:

http://www.vtk.org/Bug/view.php?id=12229

Regards
Dominik

On Thu, May 26, 2011 at 8:33 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> Hi Dominik,
>
> Thanks, I just needed confirmation of what you had done to ensure that
> the bug was specifically in vtkImageAppend and not in some other
> filter in your pipeline.
>
> Thread-related problems in the imaging filters are often due to
> incorrect assumptions by the execute methods about how the extents
> will be broken up for different threads.  I notice that vtkImageAppend
> does not have its own regression test, instead it is tested indirectly
> by Imaging/Testing/Tcl/TestAllFlips.tcl and a few others, and only for
> 2D images.
>
> If you can send a short test for it that crashes, one that can
> eventually become part of the nightly testing, that would be the best
> way to proceed.
>
>  - David
>
>
> On Thu, May 26, 2011 at 12:01 PM, Dominik Szczerba <dominik at itis.ethz.ch> wrote:
>> Yes, that was my point, it only works correctly with SetNumberOfThreads(1).
>> So there seems to be a bug, I am happy to debug and patch,
>> unfortunately, the code implementation is hardly documented...
>> Any hints are appreciated.
>> Dominik
>>
>> On Thu, May 26, 2011 at 5:58 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>> Hi Dominik,
>>>
>>> If you call SetNumberOfThreads(1) does it make the problem go away?
>>>
>>>  - David
>>>
>>>
>>> On Thu, May 26, 2011 at 9:37 AM, Dominik Szczerba <dominik at itis.ethz.ch> wrote:
>>>>
>>>> I have found that vtkImageAppend only works correctly for me
>>>> (preserving extents, overlapping regions) with one thread. With more
>>>> it crashes reported incorrect input/output pointers.
>>>> Did anybody have similar problems?
>>>>
>>>> Thanks,
>>>> Dominik
>
>