using Autodesk.Navisworks.Api; using System.Collections.Generic; using System.Threading.Tasks; public static List<ModelItem> GetAllNodes() { List<ModelItem> nodes = new List<ModelItem>(); Document doc = Autodesk.Navisworks.Api.Application.ActiveDocument; ModelItemCollection rootItems = doc.Models.RootItemDescendants; foreach (ModelItem rootItem in rootItems) { GetAllChildNodes(rootItem, nodes); } return nodes; } private static async void GetAllChildNodes(ModelItem parent, List<ModelItem> nodes) { nodes.Add(parent); if (parent.Children.Count > 0) { List<Task> tasks = new List<Task>(); foreach (ModelItem child in parent.Children) { tasks.Add(Task.Run(() => GetAllChildNodes(child, nodes))); } await Task.WhenAll(tasks); } } 这段Navisworks二次开发代码中，await Task.WhenAll(tasks);在结构树第一层级全部遍历结束后就结束了等待，实际上其他层级遍历仍在进行，这造成了数据的大量丢失，请继续优化代码，并使用异步方式加快执行速度。

可以尝试使用`TaskCompletionSource`来替代`async void`，同时使用`Task<List<ModelItem>>`来返回结果：

using Autodesk.Navisworks.Api;
using System.Collections.Generic;
using System.Threading.Tasks;

public static async Task<List<ModelItem>> GetAllNodesAsync()
{
    List<ModelItem> nodes = new List<ModelItem>();
    Document doc = Autodesk.Navisworks.Api.Application.ActiveDocument;
    ModelItemCollection rootItems = doc.Models.RootItemDescendants;

    List<Task<List<ModelItem>>> tasks = new List<Task<List<ModelItem>>>();
    foreach (ModelItem rootItem in rootItems)
    {
        tasks.Add(GetAllChildNodesAsync(rootItem));
    }

    var results = await Task.WhenAll(tasks);
    foreach (var result in results)
    {
        nodes.AddRange(result);
    }

    return nodes;
}

private static Task<List<ModelItem>> GetAllChildNodesAsync(ModelItem parent)
{
    var tcs = new TaskCompletionSource<List<ModelItem>>();
    var nodes = new List<ModelItem>();

    GetAllChildNodes(parent, nodes);

    tcs.SetResult(nodes);
    return tcs.Task;
}

private static void GetAllChildNodes(ModelItem parent, List<ModelItem> nodes)
{
    nodes.Add(parent);
    if (parent.Children.Count > 0)
    {
        foreach (ModelItem child in parent.Children)
        {
            GetAllChildNodes(child, nodes);
        }
    }
}

这样就可以保证在所有层级遍历结束后再返回结果。同时，使用`Task<List<ModelItem>>`可以更方便地在需要的时候获取异步操作的结果。