Question

我正在研究数据采集应用程序，我想确保它正常退出。也就是说，它处理所有已经收集的数据，将所有（文件）缓冲区刷新到＆＃34;磁盘＆＃34; （持久性内存），甚至可能将数据上传到云端。

所以，我写了（基于this回答）下面的代码来捕捉每一个近似事件。（这只是一个测试代码。）

问题：如果我在控制台的右上角使用X，即使终止序列仍在运行，程序也会在短暂延迟后终止。（处理程序确实被调用，并且它确实开始等待线程加入但是它会在一段时间后被终止。）如果我终止于Crt + C或Ctr + Break它按预期工作;终止序列完成并退出该过程。

问题：如何让操作系统等待我的申请终止，而不是在短暂的宽限期后将其删除？

#region Trap application termination
[DllImport("Kernel32")]
private static extern bool SetConsoleCtrlHandler(EventHandler handler, bool add);

private delegate bool EventHandler(CtrlType sig);
static EventHandler _handler;

enum CtrlType
{
    CTRL_C_EVENT = 0,
    CTRL_BREAK_EVENT = 1,
    CTRL_CLOSE_EVENT = 2,
    CTRL_LOGOFF_EVENT = 5,
    CTRL_SHUTDOWN_EVENT = 6
}

private static bool Handler(CtrlType sig, List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
    //starts new foregeound thread, so the process doesn't terminate when all the cancelled threads end
    Thread closer = new Thread(() => terminationSequence(threads, tasks, cancellationRequest));
    closer.IsBackground = false;
    closer.Start();

    closer.Join();  //wait for the termination sequence to finish

    return true; //just to be pretty; this never runs (obviously)
}
private static void terminationSequence(List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
    cancellationRequest.Cancel(); //sends cancellation requests to all threads and tasks

    //wait for all the tasks to meet the cancellation request
    foreach (Task task in tasks)
    {
        task.Wait();
    }

    //wait for all the treads to meet the cancellation request
    foreach (Thread thread in threads)
    {
        thread.Join();
    }
    /*maybe do some additional work*/
    //simulate work being done
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();
    Console.WriteLine("Spinning");
    while (stopwatch.Elapsed.Seconds < 30)
    {
        if (stopwatch.Elapsed.Seconds % 2 == 0)
        {
            Console.Clear();
            Console.WriteLine("Elapsed Time: {0}m {1}s", stopwatch.Elapsed.Minutes, stopwatch.Elapsed.Seconds);
        }
        Thread.SpinWait(10000);
    }

    Environment.Exit(0); //exit the process
}
#endregion

static void Main(string[] args)
{
    CancellationTokenSource cancellationRequest = new CancellationTokenSource();    //cancellation signal to all threads and tasks
    List<Thread> threads = new List<Thread>(); //list of threads

    //specifys termination handler
    _handler += new EventHandler((type) => Handler(type, threads, new List<Task>(), cancellationRequest));
    SetConsoleCtrlHandler(_handler, true);

    //creating a new thread
    Thread t = new Thread(() => logic(cancellationRequest.Token));
    threads.Add(t);
    t.Start();
}

Answer 1

从C＃7.1开始，您可以使用async Task Main()方法。使用此方法，您可以修改处理程序以创建方法，并在Main方法中等待它。

旁注：你应该在任何地方使用任务代替线程。任务管理你的线程更好，他们运行ThreadPool。当你创建一个新的Thread实例时，它假设它将是一个长时间运行的任务，并且windows将以不同的方式对待它。

因此，考虑到这一点，考虑将TerminateSequence方法包装在一个任务而不是一个线程中，并使该任务成为您的类的成员。现在您不必在处理程序的上下文中等待它，您可以在Main方法中等待它。

如果其余代码保持不变，您可以执行以下操作：

private Task _finalTask;

private static bool Handler(CtrlType sig, List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
    //starts new foregeound thread, so the process doesn't terminate when all the cancelled threads end
    _finalTask = Task.Run(() => terminationSequence(threads, tasks, cancellationRequest));
}

// ...

static async Task Main(string[] args)
{
    // ...

    // Wait for the termination process
    if(_finalProcess != null)
        await _finalTask
}

如果你不使用C＃7.1，你仍然可以做到这一点，它只是不那么优雅。你需要做的就是等待它：

_finalTask?.Wait();

那应该这样做。

使.NET控制台应用程序保持活动状态，直到终止序列完成

1 个答案: