[vtkusers] Delete vtk objects

[David Cole]

VTK's ref counting mechanism (C++ ++ and -- operators...) is not thread
safe. All VTK objects that have any chance of being related to each other
must all be created and destroyed from the same thread. The only way you
could use VTK objects from another thread would be to create them, use them
and destroy them completely from that thread without relating them to any
VTK objects that were created on other threads...
Does that make sense?

HTH,
David


On Tue, Aug 12, 2008 at 9:12 AM, Andreas Brüning <mail-andi at web.de> wrote:

> Hello everyone,
>
> regarding to my post from beginning of august:
>
> http://www.vtk.org/pipermail/vtkusers/2008-August/096309.html
>
> i recompiled vtk with VTK_DEBUG_LEAKS flag in CMAKE and with use of
> vtkDebugLeaks i printed out the undeleted vtkobjects right before i close
> the program . I found out that if i create vtk objects in different threads
> the delete funtionality doesnŽt work anymore. When i only create vtkobjects
> in the mainThread they delete completely. But when i create different
> threads and in there new vtkObjects, dozens of vtkobjects remain in the
> memory.Even those i never created by myself.  I call always the New() and
> Delete() methods for every vtkobject in the thread. And it happens with all
> kinds of vtkobjects.
>
> Here is an example of a thread-method:
>
>  UINT __cdecl CImageVtkWnd::ResultView_2dMPR(LPVOID lpParameter )
>  {
>
>        //managing class of the threads
>         CImageVtkWnd *pThis = static_cast<CImageVtkWnd *>(lpParameter);
>
>        ASSERT(pThis != NULL);
>
>
>        // Create the the renderer, window and interactor objects.
>        vtkRenderer *vtk_Renderer = vtkRenderer::New();
>
>        vtkWin32OpenGLRenderWindow *vtk_Win32OpenGLWindow =
> vtkWin32OpenGLRenderWindow::New();
>        vtk_Win32OpenGLWindow->AddRenderer(vtk_Renderer);
>
>        double *spacing = pThis->m_vtkvolumedata->GetSpacing();
>        vtkImageShiftScale *vtk_scale = vtkImageShiftScale::New();
>
>        vtk_scale->SetInput(pThis->m_vtkvolumedata);
>        vtk_scale->SetShift(0.5*pThis->m_dWindow - pThis->m_dLevel);
>        vtk_scale->SetScale(255.0/pThis->m_dWindow);
>        vtk_scale->ClampOverflowOn();
>        vtk_scale->SetOutputScalarTypeToUnsignedChar();
>
>        vtkImageReslice *vtkImageReslicer = vtkImageReslice::New();
>        vtkImageReslicer->SetInput(vtk_scale->GetOutput());
>        vtkImageReslicer->SetOutputDimensionality(2);
>        vtkImageReslicer->SetInterpolationModeToLinear();
>
>        vtkImageReslicer->SetOutputSpacing(spacing);
>        vtkImageReslicer->ReleaseDataFlagOn();
>
>        vtkImageActor *vtk_actor = vtkImageActor::New();
>        vtk_actor->SetInput(vtkImageReslicer->GetOutput());
>
>        vtkTransform *vtk_slicetransform        = vtkTransform::New();
>
>        vtk_Renderer->AddActor(vtk_actor);
>        vtk_Renderer->ResetCamera();
>        vtk_Renderer->GetActiveCamera()->ParallelProjectionOn();
>
>        DWORD MultiLockObj = 0;
>
>        CSyncObject* pWaitObjects[] = { pThis->m_hRenderEvent,
> pThis->m_hTerminateLoopEvent, pThis->m_hResizeEvent };
>
>        CMultiLock MultiLock( pWaitObjects, 3L );
>
>        vtk_slicetransform->Translate(pThis->m_pSliceCenter[0],
> pThis->m_pSliceCenter[1], pThis->m_pSliceCenter[2]);
>        vtk_slicetransform->RotateZ(-pThis->m_dSliceAngle_z);
>        vtk_slicetransform->RotateX(-pThis->m_dSliceAngle_x);
>        vtk_slicetransform->RotateY(-pThis->m_dSliceAngle_y);
>
>        CSize *size = new CSize(600,800);
>
>        unsigned char *tmpdata;
>
>        BITMAPINFO bmi={0};
>        bmi.bmiHeader.biSize=sizeof(BITMAPINFOHEADER);
>        bmi.bmiHeader.biPlanes=1;
>        bmi.bmiHeader.biCompression=BI_RGB;
>        bmi.bmiHeader.biBitCount=24;
>        bmi.bmiHeader.biWidth=size->cx;
>        bmi.bmiHeader.biHeight=size->cy;
>        bmi.bmiHeader.biSizeImage=size->cx * size->cy * 24;
>
>        vtk_Win32OpenGLWindow->SetSize(size->cx,size->cy);
>        vtk_Win32OpenGLWindow->OffScreenRenderingOn();
>
>        do
>        {
>                if(MultiLockObj == (WAIT_OBJECT_0+1))
>                {
>                        break;
>                }
>
>                //reslice
>                if(MultiLockObj == (WAIT_OBJECT_0+2))
>                {
>                        vtk_slicetransform->Identity();
>
>  vtk_slicetransform->Translate(pThis->m_pSliceCenter[0],
> pThis->m_pSliceCenter[1], pThis->m_pSliceCenter[2]);
>
>
>  vtk_slicetransform->RotateZ(-pThis->m_dSliceAngle_z);
>
>  vtk_slicetransform->RotateX(-pThis->m_dSliceAngle_x);
>
>  vtk_slicetransform->RotateY(-pThis->m_dSliceAngle_y);
>
>
>  vtkImageReslicer->SetResliceAxes(vtk_slicetransform->GetMatrix());
>                }
>                vtk_Win32OpenGLWindow->Render();
>
>                vtk_Renderer->ResetCamera();
>                ::EnterCriticalSection(&pThis->m_cs);
>                tmpdata =
> vtk_Win32OpenGLWindow->GetPixelData(0,0,size->cx-1, size->cy,1);
>
>                pThis->m_lbitmap->ConvertFromDIB(&bmi,(L_UCHAR *)
> tmpdata);
>
>  pThis->m_lbitmap->SetXResolution(pThis->m_iSource_resolution);
>
>  pThis->m_lbitmap->SetYResolution(pThis->m_iSource_resolution);
>                pThis->m_lbitmap->CalculateXYRes();
>                pThis->m_lbitmap->GrayScale(pThis->m_iGrayscale);
>
>                LeaveCriticalSection(&pThis->m_cs);
>
>
>
>  ::PostMessage(pThis->m_cParent->GetSafeHwnd(),WM_VTK_UPDATE_WINDOW,1,NULL);
>
>
>                delete tmpdata;
>
>
>                MultiLockObj = MultiLock.Lock( INFINITE, FALSE );
>        }
>        while(1);
>
>        //Cleanup
>        delete size;
>
>
>        vtk_Renderer->Delete();
>        vtk_Win32OpenGLWindow->Delete();
>        vtk_scale->Delete();
>        vtkImageReslicer->Delete();
>        vtk_actor->Delete();
>        vtk_slicetransform->Delete();
>
>        ::AfxEndThread( 0, true );
>        return 0L;
>
>  }
>
>
>
>
> Does anybody has an idea why i cant delete vtk objects in a thread? i tried
> already to cut the connections between vtkobjects in the different threads,
> but it also doesnŽt helped.
>
> Thanks in advance
> Andi
>
>
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