Task是.NET Framework3.0出现的，线程是基于线程池的，然后提供丰富的api，Thread方法很多很强大，但是太过强大，没有限制。

DoSomethingLong方法如下：

 /// <summary>
 /// 一个比较耗时耗资源的私有方法
 /// </summary>
 /// <param name="name"></param>
 private void DoSomethingLong(string name)
 {
     Console.WriteLine($"****************DoSomethingLong Start  {name}  {Thread.CurrentThread.ManagedThreadId.ToString("00")} {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")}***************");
     long lResult = 0;
     for (int i = 0; i < 1_000_000_000; i++)
     {
         lResult += i;
     }
     Thread.Sleep(2000);

     Console.WriteLine($"****************DoSomethingLong   End  {name}  {Thread.CurrentThread.ManagedThreadId.ToString("00")} {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")} {lResult}***************");
 }

Task的使用：

{
    Task task = new Task(() => this.DoSomethingLong("btnTask_Click_1"));
    task.Start();
}
{
    Task task = Task.Run(() => this.DoSomethingLong("btnTask_Click_2"));
}
{
    TaskFactory taskFactory = Task.Factory;
    Task task = taskFactory.StartNew(() => this.DoSomethingLong("btnTask_Click_3"));
}

 

 

 

 

 如果这样去调用：

ThreadPool.SetMaxThreads(8, 8);
for (int i = 0; i < 100; i++)
{
    int k = i;
    Task.Run(() =>
    {
        Console.WriteLine($"This is {k} running ThreadId={Thread.CurrentThread.ManagedThreadId.ToString("00")}");
        Thread.Sleep(2000);
    });
}

 

 

如果去掉设置最大线程的代码：

for (int i = 0; i < 100; i++)
{
    int k = i;
    Task.Run(() =>
    {
        Console.WriteLine($"This is {k} running ThreadId={Thread.CurrentThread.ManagedThreadId.ToString("00")}");
        Thread.Sleep(2000);
    });
}

运行结果如下：

 

 

 

 ThreadPool.SetMaxThreads(8, 8);

　　线程池是单例的，全局唯一的，设置后，同时并发的Task只有8个，而且是复用的，Task的线程是源于线程池的，全局的，请不要这样设置。

假如我想控制下Task的并发数量，改怎么做？

{
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();
    Console.WriteLine("在Sleep之前");
    Thread.Sleep(2000);//同步等待--当前线程等待2s 然后继续
    Console.WriteLine("在Sleep之后");
    stopwatch.Stop();
    Console.WriteLine($"Sleep耗时{stopwatch.ElapsedMilliseconds}");
}
{
    Stopwatch stopwatch = new Stopwatch();
    stopwatch.Start();
    Console.WriteLine("在Delay之前");
    Task task = Task.Delay(2000)
        .ContinueWith(t =>
        {
            stopwatch.Stop();
            Console.WriteLine($"Delay耗时{stopwatch.ElapsedMilliseconds}");

            Console.WriteLine($"This is ThreadId={Thread.CurrentThread.ManagedThreadId.ToString("00")}");
        });//异步等待--等待2s后启动新任务
    Console.WriteLine("在Delay之后");
    stopwatch.Stop();
    Console.WriteLine($"Delay耗时{stopwatch.ElapsedMilliseconds}");
}

运行结果如下：

　　

 

 如果将最后一个stopwatch注释掉：

 

 {
     Stopwatch stopwatch = new Stopwatch();
     stopwatch.Start();
     Console.WriteLine("在Sleep之前");
     Thread.Sleep(2000);//同步等待--当前线程等待2s 然后继续
     Console.WriteLine("在Sleep之后");
     stopwatch.Stop();
     Console.WriteLine($"Sleep耗时{stopwatch.ElapsedMilliseconds}");
 }
 {
     Stopwatch stopwatch = new Stopwatch();
     stopwatch.Start();
     Co