[vtkusers] Llvmpipe threads collapses the system when capturing a screenshot

[Utkarsh Ayachit]

Strange coincidence! We just encountered similar issue on ParaView and
it's being tracked down here:
https://gitlab.kitware.com/paraview/paraview/issues/17999

Utkarsh

On Fri, Feb 23, 2018 at 7:06 PM, Patricio Palma C. <patriciop at gmail.com> wrote:
> Thanks David.!
>
> I’ve continued debugging and I’ve noticed my VTK code works fine with Mesa
> 10.6.5 gallium 0.4 on llvmpipe (llvm 3.6)
>
> Could it be a bug in Mesa 17.0.6 gallium 0.4 on llvmpipe (llvm 4.0) the
> cause of this issue?
>
> At this moment downgrade is not an option as I also need AVX support which
> is available only from Mesa 11.1.
>
> Should I try the latest Mesa version or is there a favorited Mesa version to
> use with VTK ?
>
> Regards
> Patricio
>
>
> El El jue, 22 de feb. de 2018 a las 21:03, David Gobbi
> <david.gobbi at gmail.com> escribió:
>>
>> Hi Patricio,
>>
>> The primary thing that vtkWindowToImageFilter does is call glReadPixels()
>> via vtkOpenGLRenderWindow::GetPixelData().  So you can try
>> debugging/profiling the vtkOpenGLRenderWindow.cxx code at the point where it
>> calls glReadPixels() to see if that is where the llvmpipe threads are being
>> created.
>>
>>  - David
>>
>>
>> On Thu, Feb 22, 2018 at 4:07 PM, Patricio Palma C. <patriciop at gmail.com>
>> wrote:
>>>
>>> Hi All
>>>
>>>    I’m using vtkWindowToImageFilter to export screenshots of a
>>> vtkXOpenGLRenderWindow. It works, but every time a screenshot is created, 15
>>> new llvmpipe threads are spawned and they are not finalized by the app. I
>>> noticed this because after a while the number of threads reached the limit
>>> (about 5500) and no more threads can be spawned.
>>>
>>> This application is running linux RH 6.6 / VTK 7.1 / mesa 17.0.6
>>>
>>>
>>>
>>> Source code extract:
>>>
>>>
>>>
>>> vtkSmartPointer<vtkRenderer> osRenderer =
>>> vtkSmartPointer<vtkRenderer>::New();
>>>
>>> vtkSmartPointer<vtkXOpenGLRenderWindow> renWin =
>>> vtkSmartPointer<vtkXOpenGLRenderWindow>::New();
>>>
>>>
>>>
>>> renWin->SetOffScreenRendering(true);
>>>
>>> renWin->AddRenderer(osRenderer);
>>>
>>> renWin->SetSize(pictureSize.width(), pictureSize.height());
>>>
>>>
>>>
>>> // copyActors from QVTKWidget2
>>>
>>>
>>>
>>> vtkSmartPointer<vtkWindowToImageFilter> filter =
>>> vtkSmartPointer<vtkWindowToImageFilter>::New();
>>>
>>> filter->SetInput(renWin);
>>>
>>> filter->SetInputBufferTypeToRGB();
>>>
>>> filter->SetMagnification(1);
>>>
>>> filter->Update();
>>>
>>>
>>>
>>> vtkSmartPointer<vtkImageData> image = filter->GetOutput();
>>>
>>> …
>>>
>>> (continue using image)
>>>
>>> At this moment I’m using an empty RenderWindow, I thought actors could
>>> have a problem so I commented that out but the problem persists.
>>>
>>> After some testing I’ve noticed that the problem arise after calling
>>> filter->Update(). If this line is commented, no picture is generated but the
>>> threads are finalized.
>>>
>>> Any ideas on how can I track this issue or where should I continue
>>> looking for an issue in my code?
>>>
>>>
>>> Regards
>>>
>>> Patricio
>>>
>>> --
>>> Patricio Palma C.
>>
>>
> --
> Patricio Palma C.
>
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