[vtkusers] Memory not released when volumes are removed

[Elvis Stansvik]

2016-08-31 17:51 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> HI Robert,
>
> Den 31 aug. 2016 5:30 em skrev "Róbert Špir" <spir.robert at gmail.com>:
> >
> > Hi Elvis,
> >
> > I noticed the same behavior before ( here is the topic
> http://vtk.1045678.n5.nabble.com/memory-leak-in-
> vtkStructuredPoints-or-am-I-doing-something-wrong-tt5738805.html )
> >
> > Looks like it is the standard behavior of Linux (although very weird),
> since this is not happening in Windows or OS X.
>
> Ah right, now I remember your post. I'll do some more testing to verify
> that this is actually what's happening in my case, but it likely is.
>
I don't think this is the phenomenon I'm seeing. I tried opening the same
dataset repeatedly in my app, and I got:

77 MB
368 MB
633 MB
860 MB
1003 MB
1171 MB
1345 MB
1518 MB
1691 MB
1858 MB
2029 MB
2201 MB
2371 MB
2543 MB

So the memory usage just keeps growing, despite my attempts to clean up
before loading the dataset. This is from the RES (resident) column of top,
and I don't think this is memory which can be reclaimed by the OS? That
would show up in the VIRT (virtual) column I think.

So my question remains: Should I do something more to get a thorough
cleanup, apart from removing the vtkVolume from the renderer and deleting
it (by means of a smart pointer)?

Elvis


> Thanks,
> Elvis
>
> >
> > Best,
> >
> > Robert
> >
> >
> >
> > From: vtkusers [mailto:vtkusers-bounces at vtk.org] On Behalf Of Elvis
> Stansvik
> > Sent: Wednesday, August 31, 2016 5:19 PM
> > To: VTK Users <vtkusers at vtk.org>
> > Subject: [vtkusers] Memory not released when volumes are removed
> >
> >
> >
> > Hi all,
> >
> > Before loading a new dataset into our app, I'd like to remove all
> existing volumes from the renderer, which I believe should lead to them
> being destroyed as well, since I have no other references to the volumes
> (currently).
> >
> > What I tried was
> >
> >     // Remove all existing volumes
> >     auto volumes = renderer()->GetVolumes();
> >     volumes->InitTraversal();
> >     for (int i = 0; i < volumes->GetNumberOfItems(); ++i) {
> >         qDebug() << "removing volume";
> >         vtkSmartPointer<vtkVolume> volume = volumes->GetNextVolume();
> >         qDebug() << "before:" << volume->GetReferenceCount();
> >         renderer()->RemoveVolume(volume.GetPointer());
> >         qDebug() << "after:" << volume->GetReferenceCount();
> >     }
> >
> > The output I get each time I load a new dataset (actually the same, but
> doing it repeatedly) and execution passes by this cleanup code is:
> >
> > removing volume
> > before: 3
> > after: 1
> > removing volume
> > before: 3
> > after: 1
> > removing volume
> > before: 3
> > after: 1
> >
> > Which sort of makes sense to me: Apparently the renderer holds two
> references to the volume, since the refcount goes down by 2 when I remove
> the volume from the renderer. The remaining reference is held by the
> vtkSmartPointer I created inside the loop.
> >
> > But, what surprises me is that memory usage does not seem to go down
> when this code is executed. I would expect that when the scope of the for
> loop body is exited, the refcount will drop to zero, so the volume should
> be deleted. And I guess it probably is.
> >
> > But looking at the memory usage when repeatedly loading datasets (and
> thus clearing the previous), the resident memory used by the app
> accumulates.
> >
> > Must I somehow remove the mapper / underlying image data as well? I'm
> not holding any references to these, so I would have expected them to die
> along with the volume.
> >
> > Helpful for any tips on why this cleanup is apparently not enough to
> avoid memory accumulation.
> >
> > Thanks,
> >
> > Elvis
>
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