Freeing texture memory in SharpDX - what am I missing?

Question

I'm having a torrid time trying to resolve an issue whereby my total GPU memory consumption keeps rising throughout the course of my application, until the application fails with a DX out of memory exception.

I frequently load large textures, split into texture arrays (of type Texture2D). These are freed using .Dispose() before the next one is loaded, but memory is not seen to be freed when using Process Monitor (specifically, the "Committed GPU Memory" keeps rising with each new allocation).

1. I freely admit that I do not really know what the Committed GPU Memory metric in Process Monitor is telling me, but it is the case that the application will eventually fail through lack of memory - so the memory leak is real (and always when the memory hits the same amount in PM).

2. I do have object tracking enabled, and am able to see that no objects remain unaccounted for when the application closes normally (including after a number of texture loads).

3. I have created a synthetic example which simply allocates a texture and immediately calls Dispose() on a button click. This demonstrates the problem - memory usage increases until the application fails with an out of memory exception.

       public void d()
   {
       texture = new Texture2D(Renderer.Device, new Texture2DDescription()
       {
           Width = 1024,
           Height = 1024,
           MipLevels = 1,
           Format = Format.R8_UNorm,
           BindFlags = BindFlags.ShaderResource,
           Usage = ResourceUsage.Default,
           CpuAccessFlags = CpuAccessFlags.None,
           OptionFlags = ResourceOptionFlags.None,
           ArraySize = 100,
           SampleDescription = new SampleDescription(1, 0)
       });
       texture.Dispose();
   }
   

4. I did read somewhere on this forum that calling Flush on the context might have an effect, and in my synthetic example it does stop the memory build up - but not in my real app (?).

System is Windows 8.1, SharpDX 2.6.3.

Am I missing something really obvious here? I've Googled extensively but I can't find anything that suggests more than a Dispose is required when freeing textures.

thanks, Matt

Answer 1

Thanks for this question, I too was suffering the dreaded non-release of memory and when editing a 16Kx16K image that quickly kills your system.

To identify the problem I wrote a small app that loops around multiple times loading a Texture, creating a ShaderResourceView, then releasing the Texture and finally fixed the problem.

The link to Flush gave me the clue ...

we recommend that the application release all its references, call ID3D11DeviceContext::ClearState, and then call Flush.

I found that when I referenced the ShaderResourceView using:

device.ImmediateContext.PixelShader.SetShaderResource(0, texture.srv);

Then I had to call both ClearState and Flush

device.ImmediateContext.ClearState();
device.ImmediateContext.Flush(); 

I expect the ClearState function is performing PixelShader.SetShaderResource(0, null) and more.