c# 并行运算

c# 并行运算

1. Parallel.INVOKE() 看实例：

    private static Stopwatch watch = new Stopwatch();

        private static void Run1()
        {
            Thread.Sleep(2000);
            Console.WriteLine("Task 1 takes 2 sec");
        }
        private static void Run2()
        {
            Thread.Sleep(3000);
            Console.WriteLine("Task 2 takes 3 sec");
        }

        static void Main(string[] args)
        {
            watch.Start();
            Parallel.Invoke(Run1,Run2);
            watch.Stop();
            Console.WriteLine("Parallel run "+watch.ElapsedMilliseconds +" ms");

            watch.Restart();
            Run1();
            Run2();
            watch.Stop();
            Console.WriteLine("Normal run "+watch.ElapsedMilliseconds+" ms");

            Console.ReadLine();

看结果：

 2.Parallel.For

 看实例：

  watch.Start();
            for (int i = 0; i < 10000; i++)
            {
                for (int j = 0; j < 5000; j++)
                {
                    int sum = 0;
                    sum++;
                }
            }
            watch.Stop();
            Console.WriteLine("Normal run " + watch.ElapsedMilliseconds + "ms");

            watch.Restart();
            watch.Start();
            Parallel.For(0, 1000, item =>
              {
                  for (int j = 0; j < 5000; j++)
                  {
                      int sum = 0;
                      sum += item;
                  }

              });

            watch.Stop();
            Console.WriteLine("ParalleFor run " + watch.ElapsedMilliseconds + "ms");

            Console.ReadLine();

看结果:

是不是Parallel.For在任何时候都比for要快呢？答案当然是“不是”，要不然微软还留着for干嘛？

看实例：