如何跟踪所有线程的完成情况. C#

我需要冻结主线程直到结束递归.
递归深度=线程数.

示例代码：

BackgroundWorker backgroundWorker1;
    Random ran;

    private void Form1_Load(object sender,EventArgs e)
    {
        method();
        label1.Text = "Threads is finished";
    }


    private void method() // recursive method
    {

            Thread.Sleep(100);

            backgroundWorker1 = new BackgroundWorker();

            backgroundWorker1.DoWork +=
                new DoWorkEventHandler(backgroundWorker1_DoWork);
            backgroundWorker1.RunWorkerAsync();               //Beginning new thread
    }

    private void backgroundWorker1_DoWork(object sender,DoWorkEventArgs e)
    {
            ran = new Random();
            Thread.Sleep(ran.Next(500,1000));
            if (ran.Next(1,5) != 1) // if = 1 then to stop recursion
            {
                method();
            }
    }

线程完成后,label1.Text必须具有值“Threads is finished”.这是怎么做到的？

解决方法

控制台应用程序PoC缓存对所有已创建工作程序的引用,并使用数字变量来检查当值达到0时仍在进行的工作程序数 – 应用程序终止.如有任何问题,请告诉我.

class Program
{
    private static IList<BackgroundWorker> workers;
    private static Random ran;
    private static int activeWorkersCount;

    static void Main(string[] args)
    {            
        workers = new List<BackgroundWorker>();
        DoWork();

        while (activeWorkersCount > 0)
        {
            Thread.Sleep(200);
        }

        Console.WriteLine("Waiting for all workers to finish...");
        Console.ReadLine();
    }

    private static void DoWork() // recursive method
    {
        Thread.Sleep(100);

        var newWorker = new BackgroundWorker();

        newWorker.DoWork += BackgroundWorkerDoWork;
        newWorker.RunWorkerCompleted += (o,e) =>
               {
                  Console.WriteLine("[E] Worker finished");
                  Interlocked.Decrement(ref activeWorkersCount);
               };
        Interlocked.Increment(ref activeWorkersCount);
        newWorker.RunWorkerAsync();
    }

    private static void BackgroundWorkerDoWork(object sender,DoWorkEventArgs e)
    {
        Console.WriteLine("[S] Worker started");
        ran = new Random();
        Thread.Sleep(ran.Next(500,1000));
        if (ran.Next(1,5) != 1) // if = 1 then to stop recursion
        {
            DoWork();
        }
    }
}