SharpDX.WPF Increasing memory usage during rendering

Question

I have started working with DirectX in WPF app. My first step was to use simple library: SharpdDX.WPF. Based on samples I've implemented WPF control drawing simple line. SharpDX.WPF uses D3DImage to render images in WPF. Unfortunately application's memory increasing all time.

I implemented class TestControlRenderer : D3D10. Vertex shader is initialized like:

        var sizeInBytes = dataLength * sizeof(int) * 3;
        var bufferDescription = new BufferDescription(
            sizeInBytes,
            ResourceUsage.Dynamic,
            BindFlags.VertexBuffer,
            CpuAccessFlags.Write,
            ResourceOptionFlags.None);

        using (var stream = new DataStream(sizeInBytes, true, true))
        {
            stream.Position = 0;
            _graphDataVertexBuffer = new SharpDX.Direct3D10.Buffer(Device, stream, bufferDescription);
        }

        Device.InputAssembler.SetVertexBuffers(0, new VertexBufferBinding(_graphDataVertexBuffer, sizeof(int) * 3, 0));
        Device.InputAssembler.PrimitiveTopology = PrimitiveTopology.LineStrip;

Then constant buffer with parameters used in shader:

_controlInfoConstantBuffer = new ConstantBuffer<ControlParamsShaderData>(Device);
        Device.VertexShader.SetConstantBuffer(0, _controlInfoConstantBuffer.Buffer);

To init animation Reset method was overriden like that:

        base.Reset(args);
        if (args.RenderSize.Width == 0) return;

        _drawArgs = args;
        InitVertexBuffer(dataLength);

        _controlInfoConstantBuffer.Value = new ControlParamsShaderData
        {
            SamplesInControl = dataLength,
            MinSignalDataY = -1500,
            MaxSignalDataY = 1500
        };

        Device.VertexShader.SetConstantBuffer(0, _controlInfoConstantBuffer.Buffer);

The last step is RenderScene method:

        public override void RenderScene(DrawEventArgs args)
    {
        if (args.RenderSize.Width == 0) return;

        Device.ClearRenderTargetView(RenderTargetView, Color.Transparent);

        using (var stream = _graphDataVertexBuffer.Map(MapMode.WriteDiscard, SharpDX.Direct3D10.MapFlags.None))
        {
            for (int i = 0; i < Data.Length; i++)
            {
                stream.Write(new Vector3(i, Data[i], 0));
            }
        }
        _graphDataVertexBuffer.Unmap();
        Device.Draw(Data.Length, 0);
    }

Rendering is controlled by DispatcherTimer where OnTickMethod updates array with points coordinates and then invoke Render() method.

My question is simply, is that memory leak or something is created on each render iteration? I don't change backbuffer or create another objects. Only change Data array, update it to GPU and Shaders process it to display. My case is to display about 30 wpf controls width DirectX on one screen. Controls are with simple but realtime animation. Is that possible in that way?

Answer 1

Most likely you are leaking resources. You can see this by setting the static configuration property

SharpDX.Configuration.EnableObjectTracking = true;

then calling

SharpDX.Diagnostics.ObjectTracker.ReportActiveObjects()

at various points in your application lifetime to see if anything is leaking (at least on the SharpDX side). You can edit your code to make sure to dispose these objects. Only enable object tracking while debugging - it hurts performance.

SharpDX used to release COM objects when the finalizer ran if the object had not already been Diposed (at least as in version 2.4.2), but later disabled that (they detail why in one of their changelogs, I forget which one).

Additionally, DirectX requires that you release objects in the reverse order they were created - this can create hard-to-debug memory leaks. So when your code is

var device = new Devie(...);
var effect = new Effec(Device, byteCode);
technique = effect.GetTechniqueByName(techniqueName);
inputLayout = new InputLayout(Device, _technique.GetPassByIndex(0).Description.Signature, ...);

then your dispose code has to be

_inputLayout.Dispose();
_technique.Dispose();
_effect.Dispose();
_device.Dispose();