C＃等待多个线程完成

Question

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

这是我如何分离每个线程。下面的代码已经脱离了主要的gui线程。

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

我希望下一行代码等待，直到所有线程都完成。 我试过在那里使用t.join，但那只是线性处理它们。

Answer 1

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(); 
} 

编辑

我回头看这个，我喜欢下面更好

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

Answer 2

存放在列表中的线程结果后，他们催生和迭代名单 - 在迭代期间调用加入。你仍然线性地加入，但它应该做你想要的。

Answer 3

使用的AutoResetEvent和ManualResetEvent的职业：

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(); 
    } 


} 

Answer 4

可以使用的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(); 
    } 
} 

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(); 
} 

Answer 5

以最简单和最安全的方式这样做是为了使用CountdownEvent。请参阅Albahari。