C# -- 使用 Task 执行多线程任务

来源：cnblogs　　作者：在代码的世界里游走　　时间：2018/12/24 10:43:21　　对本文有异议

1. 使用 Task 执行多线程任务

    class Program
    {
        static void Main(string[] args)
        {
            Task task1 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(10000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            Task task2 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(20000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            Task task3 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(15000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            task1.Start();
            task2.Start();
            task3.Start();
            Console.ReadKey();
        }
        static long SumNumbers(int count)
        {
            long sum = 0;
            for (int i = 0; i < count; i++)
            {
                sum += i;
            }
            Thread.Sleep(3000);
            return sum;
        }
    }

执行结果：

2. 等待Task多线程任务执行完成

    class Program
    {
        static void Main(string[] args)
        {
            Task task1 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(10000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            Task task2 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(20000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            Task task3 = new Task(() => {
                Console.WriteLine("线程ID:{0},开始执行", Thread.CurrentThread.ManagedThreadId);
                Stopwatch stw = new Stopwatch();
                stw.Start();
                long result = SumNumbers(15000000);
                stw.Stop();
                Console.WriteLine("线程ID:{0},执行完成,执行结果:{1},执行用时{2},", Thread.CurrentThread.ManagedThreadId, result, stw.ElapsedMilliseconds);
            });
            List<Task> listTask = new List<Task>();
            listTask.Add(task1);
            listTask.Add(task2);
            listTask.Add(task3);
            task1.Start();
            task2.Start();
            task3.Start();
            Task.WaitAll(listTask.ToArray());
            Console.WriteLine("所有线程执行完成。");
            Console.ReadKey();
        }
        static long SumNumbers(int count)
        {
            long sum = 0;
            for (int i = 0; i < count; i++)
            {
                sum += i;
            }
            Thread.Sleep(3000);
            return sum;
        }
    }