C# .NET Framework 3.5 下 Task 与 Semaphore 的简单例子

使用 Thread 的请参考另一个贴子：https://www.cnblogs.com/pencilstart/p/15865400.html

注意，由于 .NET 3.5下并没有官方实现的 Task 库，所以，是通过 VS 中 NuGet 取得的 非官方 实现的 Task 库，调用接口与官方.NET 4.0 后的应该是差不多的。

 另外，Semaphore 的初始值为 1。

using System;
using System.Threading;
using System.Threading.Tasks;

namespace testTask
{
    class Program
    {
        Semaphore se = new Semaphore(1, 1);

        void test()
        {
            object param1 = new object[] { "Thread A", 1000 };
            object param2 = new object[] { "Thread B", 20 };

            Action<object> a1 = (x) => TaskProc(x);

            Task task1 = new TaskFactory().StartNew(a1, param1);
            Task task2 = new TaskFactory().StartNew(a1, param2);

            Task.WaitAll(task1, task2);
        }

        static void Main(string[] args)
        {
            Program p = new Program();

            p.test();

            Console.WriteLine("main end, mainthreadid = {0}", System.Threading.Thread.CurrentThread.ManagedThreadId);
        }

        void TaskProc(object args)
        {
            string name = (string)((object[])args)[0];
            int startdelay = (int)((object[])args)[1];

            Console.WriteLine("{0}: COME IN, threadid = {1}", name, System.Threading.Thread.CurrentThread.ManagedThreadId);

            System.Threading.Thread.Sleep(startdelay);

            Console.WriteLine("{0}: START, threadid = {1}", name, System.Threading.Thread.CurrentThread.ManagedThreadId);

            for (int i = 0; i < 10; ++i)
            {
                se.WaitOne();

                Random r = new Random();

                int s = r.Next(50, 1000);

                Console.WriteLine("{0}: i = {1}, sleep({2}), threadid = {3}", name, i, s, System.Threading.Thread.CurrentThread.ManagedThreadId);

                System.Threading.Thread.Sleep(s);

                se.Release();
            }

            Console.WriteLine("{0}: END, threadid = {1}", name, System.Threading.Thread.CurrentThread.ManagedThreadId);
        }
    }
}

//Thread A: COME IN, threadid = 3
//Thread B: COME IN, threadid = 4
//Thread B: START, threadid = 4
//Thread B: i = 0, sleep(795), threadid = 4
//Thread B: i = 1, sleep(200), threadid = 4
//Thread A: START, threadid = 3
//Thread A: i = 0, sleep(250), threadid = 3
//Thread B: i = 2, sleep(670), threadid = 4
//Thread A: i = 1, sleep(127), threadid = 3
//Thread B: i = 3, sleep(260), threadid = 4
//Thread A: i = 2, sleep(227), threadid = 3
//Thread B: i = 4, sleep(462), threadid = 4
//Thread A: i = 3, sleep(478), threadid = 3
//Thread B: i = 5, sleep(836), threadid = 4
//Thread A: i = 4, sleep(611), threadid = 3
//Thread B: i = 6, sleep(760), threadid = 4
//Thread A: i = 5, sleep(320), threadid = 3
//Thread B: i = 7, sleep(658), threadid = 4
//Thread A: i = 6, sleep(383), threadid = 3
//Thread B: i = 8, sleep(638), threadid = 4
//Thread A: i = 7, sleep(364), threadid = 3
//Thread B: i = 9, sleep(278), threadid = 4
//Thread B: END, threadid = 4
//Thread A: i = 8, sleep(89), threadid = 3
//Thread A: i = 9, sleep(192), threadid = 3
//Thread A: END, threadid = 3
//main end, mainthreadid = 1
//请按任意键继续. . .