Parallel类（简化Task 操作）

Parallel类

Parallel类是对线程的一个很好抽象。该类位于System.Threading.Tasks命名空间中，提供了数据和任务并行性。

1.用Parallel.For()方法循环

        //// simple scenario
        ParallelLoopResult result =
            Parallel.For(0, 10, async i =>
                {
                    Console.WriteLine("{0}, task: {1}, thread: {2}", i,
                       Task.CurrentId, Thread.CurrentThread.ManagedThreadId);

                    await Task.Delay(10);
                    Console.WriteLine("{0}, task: {1}, thread: {2}", i,
                      Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
                });
        Console.WriteLine("is completed: {0}", result.IsCompleted);

2.提前停止Parallel.For

For()方法的一个重载版本接受第三个Action<int, ParallelLoopState>类型的参数。使用这些参数定义一个方法，就可以调用ParallelLoopState的Break()或Stop()方法，以影响循环结果。

      // breaking early
        ParallelLoopResult result =
            Parallel.For(10, 40, (int i, ParallelLoopState pls) =>
                {
                    Console.WriteLine("i: {0} task {1}", i, Task.CurrentId);
                    Thread.Sleep(10);
                    if (i > 15)
                        pls.Break();
                });
        Console.WriteLine("Is completed: {0}", result.IsCompleted);
        if (!result.IsCompleted)
            Console.WriteLine("lowest break iteration: {0}", result.LowestBreakIteration);

3.使用Parallel.ForEach()方法循环

      string[] data = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve" };

      ParallelLoopResult result =
          Parallel.ForEach<string>(data, s =>
              {
                Console.WriteLine(s);
              });


      Parallel.ForEach<string>(data,
          (s, pls, l) =>
          {
            Console.WriteLine("{0} {1}", s, l);

          });

4.通过Parallel.Invoke()方法调用多个方法

    static void ParallelInvoke()
    {
      Parallel.Invoke(Foo, Bar);
    }

    static void Foo()
    {
      Console.WriteLine("foo");
    }

    static void Bar()
    {
      Console.WriteLine("bar");
    }

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