Question

在win表单应用程序中，我有一个如下所示的线程数组：

bool stop = false;
Thread[] threads = new Thread[10];

for (int i = 0; i < threads.Length; i++)
    threads[i] = new Thread(new ThreadStart(Job));

// How to make sure all threads have exited, when the boolean = false

void Job()
{
    while (!stop)
        // Do something
}

现在，如果用户按下STOP，stop的布尔值将设置为true，因此线程会一个接一个地退出Job方法。如何确保退出所有线程？

注意：我的情况需要传统的线程，TaskLibrary不符合我的情况。

Answer 1

使用Join方法检查所有线程是否已停止。

 foreach (var t in threads)
 {
     t.Join();
 }

Answer 2

您是否考虑过使用BackgroundWorkers？你说“传统线程”..我不完全确定你的意思，所以我不知道这是否是一个有效的提案，但这里无论如何Join()无法解决你的问题

BackgroundWorker[] workers = new BackgroundWorker[10];
bool allThreadsDone = false;

// initialize BackgroundWorkers
for (int i = 0; i < 10; i++)
{
        workers[i] = new BackgroundWorker();
        workers[i].WorkerSupportsCancellation = true;
        workers[i].RunWorkerCompleted += 
            new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
        workers[i].DoWork += new DoWorkEventHandler(AlgorithmsUI_DoWork);
        workers[i].RunWorkerAsync();
}

// thread entry point..DoWork is fired when RunWorkerAsync is called
void AlgorithmsUI_DoWork(object sender, DoWorkEventArgs e)
{
      while (!stop)
            // do something        
}

// this event is fired when the BGW finishes execution
private void  worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    bool threadsStillRunning = false;
    foreach (BackgroundWorker worker in workers)
    {
        if (worker.IsBusy)
        {
            threadsStillRunning = true;
            break;
        }
    }
    if (!threadsStillRunning)
        allThreadsDone = true;
} 

protected override OnFormClosing(FormClosingEventArgs e)
{
         if (!allThreadsDone)
         {
              e.Cancel = true;
              MessageaBox.Show("Threads still running!");
         }
}

如果任何线程仍在运行，这应该可以防止表单关闭。

Answer 3

我不确定这是否是您正在寻找的，但这是我在.NET 3.0中使用的一个简单的解决方案，以确保在继续之前完成了大量但确定的线程数：

全局：

AutoResetEvent threadPoolComplete = new AutoResetEvent(false);
static int numThreadsToRun;

激活线程时：

numThreadsToRun = [number of threads];
[start your threads];
threadPoolComplete.WaitOne();

在每个线程代码的末尾：

if (Interlocked.Decrement(ref numThreadsToRun) == 0)
{
   threadPoolComplete.Set();
}

确保退出所有线程

3 个答案: