This document discusses C# and memory management in Unity. It begins by introducing the author and some of their open-source projects related to C# and Unity, including libraries for serialization and reactive programming. It then discusses using async/await with Unity through the UniTask library. The document also covers differences in memory management between .NET Core and Unity due to using different runtimes (CoreCLR vs Unity runtime) and virtual machines. It presents examples of using unsafe code and pointers to directly manage memory in C# for cases like native collections. It concludes that while C# aims for a safe managed world, optimizations require bypassing the runtime through unsafe code, and being aware of memory can help better understand behavior and use APIs more

2. 河合 宜文 / Kawai Yoshifumi / @neuecc
New World, Inc.
C#
Unity
C#大統一理論

3. C#最速シリアライザ
https://github.com/neuecc/MessagePack-CSharp/

4. Reactive Extensions for Unity
https://github.com/neuecc/UniRx/
async/await(UniTask)
async UniTask<string> DemoAsync()
{
// You can await Unity's AsyncObject
var asset = await Resources.LoadAsync<TextAsset>("foo");
// .ConfigureAwait accepts progress callback
await SceneManager.LoadSceneAsync("scene2").ConfigureAwai
// await frame-based operation(you can also await frame c
await UniTask.Delay(TimeSpan.FromSeconds(3));
// like 'yield return WaitForEndOfFrame', or Rx's Observe
await UniTask.Yield(PlayerLoopTiming.PostLateUpdate);
// You can await standard task
await Task.Run(() => 100);
// get async webrequest
async UniTask<string> GetTextAsync(UnityWebRequest req)
{
var op = await req.SendWebRequest();
return op.downloadHandler.text;
}
var task1 = GetTextAsync(UnityWebRequest.Get("http://goog
var task2 = GetTextAsync(UnityWebRequest.Get("http://bing
var task3 = GetTextAsync(UnityWebRequest.Get("http://yaho
// concurrent async-wait and get result easily by tuple s
var (google, bing, yahoo) = await UniTask.WhenAll(task1,
// You can handle timeout easily
await GetTextAsync(UnityWebRequest.Get("http://unity.com"

6. Introduction

7. ええ、まぁ、はい。
物理エンジン
ツイーンエンジン

8. ECS is safe, pure C#...is a lie.

9. C# on Virtual Machine

10. Publishing Fall 2018
https://prodotnetmemory.com

11. CoreCLR - .NET Core Runtime System
Unity Runtime

12. https://github.com/Unity-Technologies/bdwgc
https://github.com/dotnet/coreclr/tree/master/src/vm

13. VMが違えばメモリ管理も違う

14. Stack and Heap

15. AppDomain
Thread
Stack
HeapThread
Stack

16. AppDomain
Thread
Stack
HeapThread
Stack

17. SharpLabでメモリの中身を見よう
https://sharplab.io/

28. Native Collections

29. Heap is managed, is uncontrollable

30. public unsafe struct SimpleNativeArray<T> : IDisposable where T : struct
{
void* nativeMemory;
int length;
Allocator allocator;
public SimpleNativeArray(int length, Allocator allocator)
{
var size = UnsafeUtility.SizeOf<T>() * (long)length;
this.nativeMemory = UnsafeUtility.Malloc(size, UnsafeUtility.AlignOf<T>(), allocator);
this.length = length;
this.allocator = allocator;
}
public int Length => length;
public T this[int index]
{
get => UnsafeUtility.ReadArrayElement<T>(nativeMemory, index);
set => UnsafeUtility.WriteArrayElement(nativeMemory, index, value);
}
public void Dispose()
{
UnsafeUtility.Free(nativeMemory, allocator);
}
}

32. public unsafe struct Data
{
public byte* header;
[NativeSetThreadIndex]
public int threadIndex;
public fixed int slot[JobsUtility.MaxJobThreadCount];
}

33. public struct Entity : IEquatable<Entity>
{
public int Index;
public int Version;
}

35. Conclusion

36. この世は荒野だ！
Managedで平和なC# Worldは終わった
時代はVMをどうバイパスするかに命をかける時代
(この傾向はCoreCLRも同様で、配列の代わりに裏でポインタを持つSpan<T>と
いう型を投入して同じようなことやってる）
なるべくsafeな世界に見せようという努力はそこそこ伺える
が、まぁもう隠しきれない本質的なunsafe worldがそこに……
(C#なのに!)メモリを意識することで(C#なのに!)、より挙動を理解し
やすく、また、より効率の良いAPIの使い方ができるでしょう