Garbage collection again

[StainlessTobii]

Hi Guys,

Using MonoGame for an application and I am getting massive frame rate drops every 4 or 5 seconds.

As usual this seems to be the C# garbage collector.

So I did some testing and found that my code was creating 0 garbage.

Yes I know that's rubbish, but I looked at it in detail and apart from a few strings, it is correct.

When I looked in more detail I found that the problem is rasteriser states. This paste is not going to be pretty, but it has a lot of information.

Anybody have any quick fixes for this?

Type Count Count Diff. Size (Bytes) Total Size Diff. Inclusive Size Inclusive Size Diff. Module

---

• WeakReference 17,348 +14,203 416,352 +340,872 416,352 +340,872 mscorlib.dll

• Microsoft.Xna.Framework.Graphics.RasterizerState 16,899 +14,203 1,487,112 +1,249,864 1,487,472
  +1,249,864 MonoGame.Framework.dll

  • SharpDX.Direct3D11.RasterizerState 16,894 +14,203 1,081,216 +908,992 1,081,216 +908,992 SharpDX.Direct3D11.dll

[Jjagg]

Do you create any rasterizer state instances in your code? Could you try to create a small sample that shows the issue?

What version of MonoGame are you running?

[StainlessTobii]

run time version v4.0.30319.

I do create a rasterizerstate per drawable object, but they are cached

[StainlessTobii]

Interesting, your comment made me think and I added a couple of lines of code to my draw methods.

RasterizerState old = device.RasterizerState;

Then at the end

device.RasterizerState = old;

And the garbage has gone away.........

Well I have no idea ...but it's fixed for me.

[StainlessTobii]

New information about this.

It seems to be more dangerous than I thought.

I ported an app I use a lot to MonoGame from XNA. The app uses a material caching system, so multiple meshes can share materials.

It used to create a new rasteriser state every time the material was applied to the shader. This did not create garbage collection problems in XNA. In MonoGame it made the app unusable.

So I made the rasteriser states part of the material to avoid the garbage issue, and now I cannot render the mesh because I constantly get errors because you cannot modify a rasteriser state after it has been bound to a graphics device.

I tried setting the rasteriser state to a pre-generated default state after each apply of a material, but that made no difference.

I cannot use the trick I used above, because two meshes calling Material.Apply with the same material is perfectly valid. So the old state is the same object as the new state.

I am going to write a work around that builds the rasteriser state in advance, then only changes it when an app setting is changed, but someone needs to look at this.

1) I never had problems with garbage collection before, it's constant now with MonoGame.
2) I never had a binding issue with rasteriser states before.

Something is wrong here. If you can point be at the relevant source code I will have a look for you.

Cheers guys

[Jjagg]

It used to create a new rasteriser state every time the material was applied to the shader.

That's not a good idea. You should cache all your render state instances since they wrap native resources. Maybe XNA caches the instances.

now I cannot render the mesh because I constantly get errors because you cannot modify a rasteriser state after it has been bound to a graphics device.

Why don't you just initialize the rasterizer state when creating it and don't try to modify it again?

I tried setting the rasteriser state to a pre-generated default state after each apply of a material, but that made no difference.

Can you clarify this? What issue did you run into?

1) I never had problems with garbage collection before, it's constant now with MonoGame.

My gut says the problem is not garbage collection. Did you actually profile this?

2) I never had a binding issue with rasteriser states before.

You mean the error when modifying after binding? That behavior is identical to XNA.

[willmotil]

Posting a snippet is always good.

Forgive me if you already know this, but since you mentioned that you got the error cant modify the rasterstate on the graphics object. I thought i should post a example as the syntax for caching renderstates is a little un-intuitive.

Excuse the lack of code casing below.

            // some often used states
            public static class MyStates
            {
                public static RasterizerState rs_regular = new RasterizerState()
                {
                    FillMode = FillMode.Solid,
                    CullMode = CullMode.CullCounterClockwiseFace,
                    MultiSampleAntiAlias = false
                };
                public static RasterizerState rs_solid_nocull = new RasterizerState()
                {
                    FillMode = FillMode.Solid,
                    CullMode = CullMode.None
                };
                public static RasterizerState rs_solid_ccw = new RasterizerState()
                {
                    FillMode = FillMode.Solid,
                    CullMode = CullMode.CullCounterClockwiseFace
                };
                public static RasterizerState rs_solid_cw = new RasterizerState()
                {
                    FillMode = FillMode.Solid,
                    CullMode = CullMode.CullClockwiseFace
                };
                public static RasterizerState rs_wireframe_cullnone = new RasterizerState()
                {
                    FillMode = FillMode.WireFrame,
                    CullMode = CullMode.None
                };
                public static DepthStencilState ds_depthtest_lessthanequals = new DepthStencilState()
                {
                    DepthBufferEnable = true,
                    DepthBufferFunction = CompareFunction.LessEqual
                };
                public static DepthStencilState ds_depthtest_less = new DepthStencilState()
                {
                    DepthBufferEnable = true,
                    DepthBufferFunction = CompareFunction.Less
                };
                public static DepthStencilState ds_depthtest_greater = new DepthStencilState()
                {
                    DepthBufferEnable = true,
                    DepthBufferFunction = CompareFunction.Greater
                };
                public static DepthStencilState ds_depthtest_disabled = new DepthStencilState()
                {
                    DepthBufferEnable = false,
                };
                public static SamplerState ss_point_clamp = new SamplerState()
                {
                    Filter = TextureFilter.Point,
                    AddressU = TextureAddressMode.Clamp,
                    AddressV = TextureAddressMode.Clamp,
                    AddressW = TextureAddressMode.Clamp
                };
            }

then in draw

protected override void Draw(GameTime gameTime)
{
    GraphicsDevice.Clear(Color.Black);

    GraphicsDevice.DepthStencilState = Gh.MyStates.ds_depthtest_less;
    GraphicsDevice.RasterizerState = Gh.MyStates.rs_solid_cw;

    basicQuadDrawEffect.SetQuadDrawParameters(meshObject.GetTheWorldViewProjection, texture);

    if (keyoptWireframe == 1)
        GraphicsDevice.RasterizerState = Gh.MyStates.rs_wireframe_cullnone;
    else
        GraphicsDevice.RasterizerState = Gh.MyStates.rs_solid_nocull;

            // ^^ there is a bit of overhead to setting the states to the device.
            
            basicQuadDrawEffect.SetQuadDrawParameterTexture(texture2);

            if (keyoptOldMesh == 1)
                DrawMesh(basicQuadDrawEffect.testEffect);
            else
            {
                if (keyoptOldMesh == 3)
                    DrawMesh3(basicQuadDrawEffect.testEffect);
                else
                    DrawMesh2(basicQuadDrawEffect.testEffect);
            }

basically you want to batch i.e. set the state then draw everything that uses that state.

[StainlessTobii]

Jjagg,

I do initialise the raster state when I create it, but I also allow dynamic changes to raster state.

I am pretty sure the binding issue is either a bug, or we have a design I hate.

Think of it this way....

Create RasterStateA.
Create RasterStateB.

Bind RasterStateA  and renderer. All good.
BInd RasterStateB  and render. All good.
Modify RasterStateA   CRASH (Cannot modify a rasterstate after being bound to a GraphicsDevice)

Once you bind RasterStateB you should be able to modify RasterStateA. unless they are using the memory block in place instead of doing a copy.I personally hate that practice. I have had to fix so many hard to find bugs in games caused by this practice.

The problem definitely is the garbage collection. Not only can I see the GC in visual studio, I can run reports and see what garbage is being collected.

Willmotil,

Yes that's basically what I ended up doing