任务并行库 - 知道所有任务何时完成 [英] Task Parallel Library - Know when all tasks are finished

问题描述

我使用任务并行库来启动一些任务，如下所示：

  public static void Main（）
 {
 for（var i = 0; i <10; i ++）
 {
 var x = i; 
 Task.Factory.StartNew（（）=> new WorkerClass（x）.Do（））; 
} 
 
 //（*）这里我想等待所有任务完成
 Task.WaitAll（）; 
 
 Console.WriteLine（Ready。）; 
 Console.ReadLine（）; 
} 
  

问题是某些任务可以自己创建新任务。这是 WorkerClass 的样子：

  public class WorkerClass 
 {
 private static readonly NLog.Logger Log = NLog.LogManager.GetCurrentClassLogger（）; 
 
 private readonly int _i; 
 
 public WorkerClass（int i）
 {
 _i = i; 
} 
 
 public void Do（）
 {
 if（_i％3 == 0）
 Task.Factory.StartNew（（）=> ; new WorkerClass（_i + 101）.Do（））; 
 
 Log.Info（Started {0}，_i）; 
 Thread.Sleep（2000）; 
 Log.Info（Done {0}，_i）; 
} 
} 
  

对于 i

我希望能等到所有任务（包括那些任务）

有没有干净/内置的方法来做这个（有或没有TPL）？

解决方案

保留对所有顶级任务的引用，然后使用 WaitAll ：

  var tasks = new Task [10]; 
 for（var i = 0; i <10; i ++）
 {
 var x = i; 
 tasks [i] = Task.Factory.StartNew（（）=> new WorkerClass（x）.Do（））; 
} 
 
 Task.WaitAll（tasks）; 
  

对于子任务，只要确保将它们附加到父任务。这意味着父任务在所有子任务也完成之前不会进入完整状态。

  Task.Factory.StartNew （（）=> {}，TaskCreationOptions.AttachedToParent）; 
  

I use Task Parallel Library to start some tasks, like so:

    public static void Main()
    {
        for (var i = 0; i < 10; i++)
        {
            var x = i;
            Task.Factory.StartNew(() => new WorkerClass(x).Do());
        }

        // (*) Here I'd like to wait for all tasks to finish
        Task.WaitAll(); 

        Console.WriteLine("Ready.");
        Console.ReadLine();
    }

The problem is that some tasks can create new tasks themselves. This is how WorkerClass looks like:

public class WorkerClass
{
    private static readonly NLog.Logger Log = NLog.LogManager.GetCurrentClassLogger();

    private readonly int _i;

    public WorkerClass(int i)
    {
        _i = i;
    }

    public void Do()
    {
        if (_i % 3 == 0)
            Task.Factory.StartNew(() => new WorkerClass(_i + 101).Do());

        Log.Info("Started {0}", _i);
        Thread.Sleep(2000);
        Log.Info("Done {0}", _i);
    }
}

For every value of i that's a multiple of 3, a new Task is started.

I'd like to be able to wait until all tasks (including the ones created by other tasks) are finished.

Is there a clean/built-in way to do this (with or without TPL)?

解决方案

Keep a reference to all top-level tasks and then just use WaitAll:

    var tasks = new Task[10];
    for (var i = 0; i < 10; i++)
    {
        var x = i;
        tasks[i] = Task.Factory.StartNew(() => new WorkerClass(x).Do());
    }

    Task.WaitAll( tasks );

As for the child tasks, just make sure you attach them to the parent task. This means that the parent task will not go into a complete state until all child tasks are also finished.

    Task.Factory.StartNew(() => { }, TaskCreationOptions.AttachedToParent);

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