C# 等待多个线程完成

C# Waiting for multiple threads to finish

提问by Andy

I have a windows forms app that I am checking all the serial ports to see if a particular device is connected.

我有一个 Windows 窗体应用程序，我正在检查所有串行端口以查看是否连接了特定设备。

This is how I spin off each thread. The below code is already spun off the main gui thread.

这就是我如何分离每个线程。下面的代码已经从主 gui 线程中分离出来。

foreach (cpsComms.cpsSerial ser in availPorts)
{
    Thread t = new Thread(new ParameterizedThreadStart(lookForValidDev));
    t.Start((object)ser);//start thread and pass it the port
}

I want the next line of code to wait until all the threads have finished. I've tried using a t.joinin there, but that just processes them linearly.

我希望下一行代码等到所有线程都完成。我试过t.join在那里使用 a ，但这只是线性处理它们。

采纳答案by Yuriy Faktorovich

List<Thread> threads = new List<Thread>();
foreach (cpsComms.cpsSerial ser in availPorts)
{
    Thread t = new Thread(new ParameterizedThreadStart(lookForValidDev));
    t.Start((object)ser);//start thread and pass it the port
    threads.Add(t);
}
foreach(var thread in threads)
{
    thread.Join();
}

Edit

编辑

I was looking back at this, and I like the following better

我正在回顾这个，我更喜欢以下内容

availPorts.Select(ser =>
      {
          Thread thread = new Thread(lookForValidDev);
          thread.Start(ser);
          return thread;
      }).ToList().ForEach(t => t.Join());

回答by NG.

Store the Thread results in a list after they were spawned and iterate the list - during iteration call join then. You still join linearly, but it should do what you want.

在产生线程结果并迭代该列表后，将它们存储在一个列表中——然后在迭代调用 join 期间。你仍然线性加入，但它应该做你想做的。

回答by Islam Yahiatene

Use the AutoResetEvent and ManualResetEvent Classes:

使用 AutoResetEvent 和 ManualResetEvent 类：

private ManualResetEvent manual = new ManualResetEvent(false);
void Main(string[] args)
{
    AutoResetEvent[] autos = new AutoResetEvent[availPorts.Count];

    manual.Set();

    for (int i = 0; i < availPorts.Count - 1; i++)
        {

        AutoResetEvent Auto = new AutoResetEvent(false);
        autos[i] = Auto;

        Thread t = new Thread(() => lookForValidDev(Auto, (object)availPorts[i]));
        t.Start();//start thread and pass it the port  

    }
    WaitHandle.WaitAll(autos);
    manual.Reset();

}


void lookForValidDev(AutoResetEvent auto, object obj)
{
    try
    {
         manual.WaitOne();
         // do something with obj 
    }
    catch (Exception)
    {

    }
    finally
    {
        auto.Set();
    }


} 

回答by Kiril

You can use a CountDownLatch:

您可以使用 CountDownLatch：

public class CountDownLatch
{
    private int m_remain;
    private EventWaitHandle m_event;

    public CountDownLatch(int count)
    {
        Reset(count);
    }

    public void Reset(int count)
    {
        if (count < 0)
            throw new ArgumentOutOfRangeException();
        m_remain = count;
        m_event = new ManualResetEvent(false);
        if (m_remain == 0)
        {
            m_event.Set();
        }
    }

    public void Signal()
    {
        // The last thread to signal also sets the event.
        if (Interlocked.Decrement(ref m_remain) == 0)
            m_event.Set();
    }

    public void Wait()
    {
        m_event.WaitOne();
    }
}

Example how to use it:

示例如何使用它：

void StartThreads
{
    CountDownLatch latch = new CountDownLatch(availPorts.Count);

    foreach (cpsComms.cpsSerial ser in availPorts)
    {
        Thread t = new Thread(new ParameterizedThreadStart(lookForValidDev));

        //start thread and pass it the port and the latch
        t.Start((object)new Pair(ser, latch));

    }

    DoSomeWork();

    // wait for all the threads to signal
    latch.Wait();

    DoSomeMoreWork();
}

// In each thread
void NameOfRunMethod
{
    while(running)
    {
        // do work
    }

    // Signal that the thread is done running
    latch.Signal();
}

回答by IamIC

The simplest and safest way to do this is to use a CountdownEvent. See Albahari.

最简单和最安全的方法是使用 CountdownEvent。见阿尔巴哈里。