Hey there! Let's dig into your Unity terrain generation problem and sort out how to fix the stuttering, plus help you decide between general multithreading and Unity's Job System.

First, Why Your Current Code Causes Stuttering #

Looking at your code, here are the key issues:

• Only one worker thread at a time: You're starting a single thread, waiting for it to finish, then starting another. This means you're not actually leveraging multiple CPU cores—you're just offloading work to a single background thread, so the main thread still has to process chunks one by one, leading to noticeable stutters.
• Thread-unsafe collections: You're using List<AngularWP> for awps and renderList, which aren't thread-safe. When your worker thread modifies these lists while the main thread is reading/writing them, you can get race conditions, unexpected behavior, and even crashes (even if you haven't seen them yet).
• Misplaced Unity API calls: If awp.renderMesh() or setup()/refreshMesh() modify Unity objects (like Mesh or GameObject), doing this in a background thread is risky—most Unity APIs are only safe to call from the main thread. Your current code might be getting away with it, but it's a ticking time bomb.
• Unnecessary Thread.Sleep(1): This just wastes time in your worker thread for no reason—remove it.

Optimizing General Multithreading for Your Project #

If you want to stick with general multithreading (great for learning fundamentals that apply outside Unity), here's how to fix your code:

1. Use thread-safe collections: Replace List<AngularWP> with ConcurrentQueue<AngularWP> for both awps and renderList. This lets multiple threads add/remove items safely without race conditions.
2. Use a thread pool instead of manual threads: Creating a new Thread for each chunk is inefficient. Instead, use ThreadPool.QueueUserWorkItem or Task.Run (if your Unity version supports it) to queue terrain generation tasks. This lets the system manage thread creation/reuse efficiently.
3. Separate computation from Unity API calls: Do all the heavy lifting (voxel data generation, vertex/triangle calculations) in the background thread, but only modify Unity objects (Mesh, GameObject) in the main thread. For example:
   • In your worker thread, calculate vertex positions, normals, and triangle indices, and store them in fields on AngularWP (like Vector3[] vertices, int[] triangles).
   • Then add awp to the thread-safe renderList, and in the main thread's Update, pull items from the queue and call setup()/refreshMesh() to apply the computed data to the Mesh.
4. Limit concurrency: Don't flood the thread pool with hundreds of tasks at once. Use a semaphore or limit the number of active tasks to match your CPU core count (e.g., Environment.ProcessorCount - 1 to leave one core for the main thread).

Example snippet for thread-safe queue handling:

private ConcurrentQueue<AngularWP> awps = new ConcurrentQueue<AngularWP>();
private ConcurrentQueue<AngularWP> renderList = new ConcurrentQueue<AngularWP>();

void Update() {
    // Process render queue in main thread
    if (renderList.TryDequeue(out var awp)) {
        awp.setup();
        awp.refreshMesh();
        awp.finalize();
        awp.initialPhysicsSetup();
        awp.setPosition(new Vector3(awp.position.x, 0, awp.position.z));
    }

    // Queue multiple tasks if available (adjust concurrency as needed)
    int tasksToQueue = Math.Min(4, awps.Count); // Limit to 4 concurrent tasks
    for (int i = 0; i < tasksToQueue; i++) {
        if (awps.TryDequeue(out var wp)) {
            ThreadPool.QueueUserWorkItem(state => {
                var targetWp = state as AngularWP;
                // Do heavy computation here (voxel generation, vertex calculation)
                targetWp.CalculateMeshData(); // Your new method that only computes data, no Unity API calls
                renderList.Enqueue(targetWp);
            }, wp);
        }
    }
}

Should You Switch to Unity's Job System? #

Let's weigh the pros and cons for your situation:

• Pros of Job System:
  • Built for Unity: It's designed to play nicely with Unity's main thread and avoids common multithreading pitfalls (like accidental Unity API calls from background threads).
  • Burst Compiler: When paired with Burst, your terrain generation code can run significantly faster than regular C# code, thanks to LLVM optimizations.
  • Easy parallelization: IJobParallelFor lets you process chunks or voxels in parallel with minimal code, without managing threads manually.
• Cons of Job System:
  • Unity-specific: The knowledge doesn't directly translate to non-Unity projects (though the parallelization concepts do).
  • Learning curve: You'll need to learn about job dependencies, native containers, and Burst restrictions (like no managed objects in jobs).

Recommendation #

• If your primary goal right now is to fix the stuttering in your Unity game quickly, start with optimizing your general multithreading code (thread-safe collections, thread pools, separating compute/Unity calls). It's a small change that will give you immediate results.
• If you plan to keep working on Unity projects long-term, invest time in learning the Job System + Burst. It's the most efficient way to handle compute-heavy tasks in Unity, and once you get the hang of it, you'll never want to go back to manual threads for Unity work.
• If you want to learn skills that apply to all C# projects, master general multithreading first, then learn the Job System as a Unity-specific extension—they complement each other, not compete.

Final Notes #

Whichever path you choose, remember that Unity's main thread should only handle UI, input, and Unity API calls—all heavy computation should happen in background threads or jobs. This is the key to eliminating stutters in your terrain generation.

内容的提问来源于stack exchange，提问作者Connor