如何查看在Parallel.ForEach循环中引发的线程数？

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

        HashSet<int> threadIds = new HashSet<int>();

        Parallel.ForEach(numbers, (number) =>
        {
            int threadId = Thread.CurrentThread.ManagedThreadId;
            threadIds.Add(threadId);

            // 其他操作...

        });

        Console.WriteLine("在Parallel.ForEach循环中引发的线程数：" + threadIds.Count);
    }
}