如何使用tpl分別監視和停止運行任務

Question

我不熟悉並行編程和c＃中的tpl，我正在進行以下測試，以便了解任務的工作原理。 每次單擊button1並觸發有界方法時，都會啟動一個新任務。 當我單擊button_2時，所有任務都將退出循環，我將獲得所有任務和任務ID的時間。

那么有沒有辦法在他們在任務池中工作時監視這些任務，所以如果我希望單獨使用任務ID，我可以阻止它們？

        Boolean stopprogramm = false;
        private void button1_Click(object sender, EventArgs e)
        {

            Task timerTask1 = Task.Factory.StartNew(() =>
                {
                    Stopwatch watch = new Stopwatch();
                    watch.Start();
                    while (stopprogramm == false)
                    {
                        //Do some work
                    }
                    Console.WriteLine("time ellapsed for No partitioning at all version {0}ms , thread id was {1}", watch.ElapsedMilliseconds, Task.CurrentId);
                    watch.Stop();

                });


        }
        private void button2_Click(object sender, EventArgs e)
        {
            stopprogramm = true;
        }

Answer 1

像這樣的東西可以工作。

    private Dictionary<Guid, TaskTracker> _taskMap = new Dictionary<Guid, TaskTracker>();

    private void OnButton1Click(object sender, EventArgs eventArgs)
    {
        TaskTracker taskTracker = new TaskTracker(Guid.NewGuid(), OnDoWork);
        _taskMap.Add(taskTracker.Identity, taskTracker);
        taskTracker.Run();
    }

    private void OnDoWork()
    {
        // Do some work
    }

    private void OnButton2Click(object sender, EventArgs eventArgs)
    {
        Guid identity = _taskMap.Count > 0 ? _taskMap.First().Value.Identity : default(Guid);  // find some way to get the desired task

        TaskTracker taskTracker;
        if (_taskMap.TryGetValue(identity, out taskTracker))
        {
            taskTracker.TaskExiting += OnTaskExiting;
            taskTracker.Stop();
        }
    }

    private void OnTaskExiting(object sender, EventArgs eventArgs)
    {
        TaskTracker taskTracker = (TaskTracker)sender;
        taskTracker.TaskExiting -= OnTaskExiting;
        _taskMap.Remove(taskTracker.Identity);
        // do what you want with the timings
    }

任務的類是這樣的：

public class TaskTracker
{
    private readonly Action OnDoWork;
    private Task _task;
    private bool _isRunning = true;

    public TaskTracker(Guid identity, Action onDoWork)
    {
        Identity = identity;
        OnDoWork = onDoWork;
    }

    public readonly Guid Identity;
    public readonly Stopwatch Stopwatch = new Stopwatch();

    public event EventHandler TaskExiting;

    public void Run()
    {
        Task _task = Task.Factory.StartNew(
            () =>
                {
                    Stopwatch.Start();
                    try
                    {
                        while (_isRunning)
                        {
                            OnDoWork();
                        }
                        if (TaskExiting != null)
                        {
                            TaskExiting(this, EventArgs.Empty);
                        }
                    }
                    finally
                    {
                        Stopwatch.Stop();
                    }
                }
            );
    }

    public void Stop()
    {
        _isRunning = false;
        // wait for task to exit?
        _task = null;
    }
}

您需要填寫空白，意味着跟蹤任務並在按下按鈕2時獲取目標任務。

Answer 2

您在我的其他答案中的一條評論中提到了一個鏈接，看起來該鏈接描述了如何使其可取消。 我已經調整了我的例子來支持這個：

    private Dictionary<Guid, TaskTracker> _taskMap = new Dictionary<Guid, TaskTracker>();

    private void OnButton1Click(object sender, EventArgs eventArgs)
    {
        TaskTracker taskTracker = new TaskTracker(Guid.NewGuid(), OnDoWork);
        _taskMap.Add(taskTracker.Identity, taskTracker);
        taskTracker.Start();
    }

    private void OnDoWork(CancellationToken token)
    {
        for (int i = 0; i < 100; i++)
        {
            Thread.Sleep(100); // Do some work, checking if cancel requested every once in a while
            if (token.IsCancellationRequested)
            {
                token.ThrowIfCancellationRequested();
            }
        }
    }

    private void OnButton2Click(object sender, EventArgs eventArgs)
    {
        Guid identity = _taskMap.Count > 0 ? _taskMap.First().Value.Identity : default(Guid);  // find some way to get the desired task

        TaskTracker taskTracker;
        if (_taskMap.TryGetValue(identity, out taskTracker))
        {
            taskTracker.TaskExiting += OnTaskExiting;
            taskTracker.Stop();
        }
    }

    private void OnTaskExiting(object sender, EventArgs eventArgs)
    {
        TaskTracker taskTracker = (TaskTracker)sender;
        taskTracker.TaskExiting -= OnTaskExiting;
        _taskMap.Remove(taskTracker.Identity);

        Console.WriteLine("Time ellapsed for No partitioning at all version {0}ms , thread id was {1}", taskTracker.Stopwatch.ElapsedMilliseconds, Task.CurrentId);
    }

    private void OnButton3Click(object sender, EventArgs eventArgs)
    {
        Guid identity = _taskMap.Count > 0 ? _taskMap.First().Value.Identity : default(Guid);  // find some way to get the desired task

        TaskTracker taskTracker;
        if (_taskMap.TryGetValue(identity, out taskTracker))
        {
            taskTracker.TaskExiting += OnTaskExiting;
            taskTracker.Cancel();
        }
    }

這是TaskTracker類：

public class TaskTracker
{
    private readonly Action<CancellationToken> OnDoWork;
    private readonly CancellationTokenSource TokenSource;
    private readonly CancellationToken Token;

    private bool _isRunning;
    private Task _task;

    public TaskTracker(Guid identity, Action<CancellationToken> onDoWork)
    {
        TokenSource = new CancellationTokenSource();
        Token = TokenSource.Token;

        Identity = identity;
        OnDoWork = onDoWork;
    }

    public readonly Guid Identity;
    public readonly Stopwatch Stopwatch = new Stopwatch();

    public event EventHandler TaskExiting;

    public void Start()
    {
        _isRunning = true;
        _task = Task.Factory.StartNew(
            () =>
                {
                    Stopwatch.Start();
                    try
                    {
                        while (_isRunning)
                        {
                            OnDoWork(Token);
                        }
                    }
                    finally
                    {
                        Stopwatch.Stop();

                        if (TaskExiting != null)
                        {
                            TaskExiting(this, EventArgs.Empty);
                        }
                    }
                }, Token
            );
    }

    public void Stop(bool waitForTaskToExit = false)
    {
        if (_task == null)
        {
            throw new InvalidOperationException("Task hasn't been started yet");
        }

        _isRunning = false;
        if (waitForTaskToExit)
        {
            _task.Wait();
        }
        _task = null;
    }

    public void Cancel()
    {
        if (_task == null)
        {
            throw new InvalidOperationException("Task hasn't been started yet");
        }

        _isRunning = false;
        TokenSource.Cancel();
        _task = null;
    }
}

基本上，在你的“工作者”中，你會檢查令牌是否表明它被取消，如果是，那么做一些清理，然后調用令牌上的方法ThrowIfCancellationRequested爆發。