C#多线程技术总结(异步)

我这里针对现有的C#多线程技术进行一个汇总,一是复习,二是方便索引,文章部份知识点来源于网络,非本人原创。html

1、并行(异步):编程

1.System.Threading.Tasks命名空间下的(TPL):网络

1.1:Parallel.Invoke --并行执行多个任务,主线程等待并行执行完毕后才开始续续运行。多线程

示例:dom

        static void Main(string[] args)
        {
            Parallel.Invoke(new ParallelOptions() { MaxDegreeOfParallelism=2},Run1,Run2);
            Console.WriteLine("我是主线程!");
            Console.Read();
        }

        static void Run1()
        {
            Console.WriteLine("我是任务一,我运行3s");
            Thread.Sleep(3000);
            Console.WriteLine("任务一执先完成");
        }

        static void Run2()
        {
            Console.WriteLine("我是任务二,我运行5s");
            Thread.Sleep(5000);
            Console.WriteLine("任务二执先完成");
        }

1.2:Parallel.For--循环迭代多个任务,多个任务之间存在并行状况,主线程等待循环迭代的多个任务执行完毕后才开始续续运行。异步

示例:async

Parallel.For(0, 10, (i) => {
                Console.WriteLine("我是第{0}个任务,线程ID是:{1}",i,Thread.CurrentThread.ManagedThreadId);
                Thread.Sleep(new Random().Next(10) * 10 * 500);
                Console.WriteLine("线程ID是:{0}执行完成", Thread.CurrentThread.ManagedThreadId);
            });

1.3:Parallel.ForEach--循环迭代多个任务,多个任务之间存在并行状况,主线程等待循环迭代的多个任务执行完毕后才开始续续运行。注意它有多个重载方法异步编程

示例:线程

            var bag = new ConcurrentBag<int>();

            Parallel.ForEach(Partitioner.Create(0, 100), i =>
            {
                for (int m = i.Item1; m < i.Item2; m++)
                {
                    bag.Add(m);
                    Console.WriteLine("我是第{0}个任务,线程ID是:{1}", m, Thread.CurrentThread.ManagedThreadId);
                }
            });
            Console.WriteLine("并行计算:集合有:{0}", bag.Count);

1.4:TAP(基于任务的异步编),使用Task类 (注意:默认任务开启后,会在新线程中执行,主线程不会等待任务而是继续下面的执行,若使用Task.WaitAll,则会等待相应的任务完成后才会执行)htm

示例:

//第一种方式启动
var task1 = new Task(() => //实例化
            {
                Run1();
            });

task1.Start(); //启动

 //第二种方式开启
 var task2 = Task.Factory.StartNew(() => //直接建立任务并启动
            {
                Run2();
            });

//主线程等待任务执行完
 Task.WaitAll(task1, task2);

2.ParallelEnumerable类中的扩展方法(先将枚举对象使用AsParallel转换成ParallelQuery类型,而后就能够使用ParallelQuery在ParallelEnumerable类相关的扩展方法)

示例:

var resultList = testList.AsParallel().Where(i=>i>=100).ToList();
 Console.WriteLine("resultList Count:{0}", resultList.Count);

3.建立新Thread--新线程启动后,主线程与建立的线程各自执行,若须要主线程等待异步线程执行完成后才执行,则应使用asyncThread.Join方法。

示例:

        static void AsyncThreadMethod()
        {
            Console.WriteLine("我是异步执行线程,线程ID是:{0}", Thread.CurrentThread.ManagedThreadId);
        }

        static void AsyncThreadMethod(object state)
        {
            Console.WriteLine("我是异步执行线程,线程ID是:{0},状态:{1}", Thread.CurrentThread.ManagedThreadId,state);
        }


//建立线程并执行
            Thread asyncThread = new Thread(new ThreadStart(AsyncThreadMethod));
            asyncThread.IsBackground = true;
            asyncThread.Start();

            Thread asyncThread2 = new Thread(new ParameterizedThreadStart(AsyncThreadMethod));
            asyncThread2.IsBackground = true;
            asyncThread2.Start("这是来自主线程的参数");

4.使用ThreadPool.QueueUserWorkItem静态方法--WaitCallback回调方法要求其必需带一个object的参数

示例:

 ThreadPool.QueueUserWorkItem(new WaitCallback(AsyncThreadMethod));//不带参数,则系统将state自动设为null

ThreadPool.QueueUserWorkItem(new WaitCallback(AsyncThreadMethod), "这是来自主线程的参数");

5.APM(异步编程模型),利用BeginInvoke与EndInvoke完成异步执行委托方法

示例:

            Func<string, string> funcDelegate = (s) =>
            {
                Console.WriteLine("我是Func委托方法!");
                return "委托方法参数:" + s;
            };

            //1.无阻塞异步回调
            var aysncResult = funcDelegate.BeginInvoke("这是来自主线程的参数", new AsyncCallback((result) =>
            {
                //获取委托对象,调用EndInvoke方法获取运行结果
                AsyncResult _result = (AsyncResult)result;
                var func = (Func<string, string>)_result.AsyncDelegate;
                string data = func.EndInvoke(_result);
                Console.WriteLine(data +",附加参数:" + _result.AsyncState.ToString());
            }),"其它参数");

            //2.阻塞主线程,使主线程等待执行完毕
            string data2 = null;
            var aysncResult2 = funcDelegate.BeginInvoke("这是来自主线程的参数2", null, null);

            data2 = funcDelegate.EndInvoke(aysncResult2);//第一种阻塞方法

            while (!aysncResult2.IsCompleted) //第二种阻塞方法
            {
                Thread.Sleep(200);      //虚拟操做
                Console.WriteLine("主线程等待...");
            }
            data2 = funcDelegate.EndInvoke(aysncResult2);

            WaitHandle[] waitHandles = new WaitHandle[]{ aysncResult2.AsyncWaitHandle };
            while (WaitHandle.WaitAll(waitHandles, 5000)) //第三种阻塞方法
            {
                Console.WriteLine("主线程等待...");
            }

6. EAP(基于事件的异步编程)--主要用在客户端应用程序中

示例:

            //例子一
            var client = new WebClient();
            client.DownloadProgressChanged += delegate(object s, DownloadProgressChangedEventArgs e)
            {
                Console.WriteLine("Download Percent:{0}", e.ProgressPercentage);
            };
            client.DownloadStringCompleted += delegate(object s,DownloadStringCompletedEventArgs e){
                Console.WriteLine("Download Content Length:{0}",e.Result.Length);
                Console.WriteLine("Download Completed!");
            };
            
            client.DownloadStringAsync(new Uri("http://www.zuowenjun.cn"));

            

            //例子二
            BackgroundWorker worker = new BackgroundWorker();
            worker.DoWork += (s, e) => {
                Console.WriteLine("异步执行中。。。");
            };
            worker.RunWorkerCompleted += (s, e) => {
                Console.WriteLine("异步执行完成。。。");
            };
            worker.RunWorkerAsync();

7.async和await关键字

示例:

	public Task<double> GetValueAsync(double num1, double num2)
	{
		return Task.Run(() =>
		{
			for (int i = 0; i < 1000000; i++)
			{
				num1 = num1 / num2;
			}
			return num1;
		});
	}
	public async void DisplayValue()
	{
		double result = await GetValueAsync(1234.5, 1.01);//此处会开新线程处理GetValueAsync任务,而后方法立刻返回
		//这以后的全部代码都会被封装成委托,在GetValueAsync任务完成时调用
		System.Diagnostics.Debug.WriteLine("Value is : " + result);
	}

//调用
DisplayValue();//不会阻塞主线程

 参考如下相关文章:

C#综合揭秘——细说多线程(上)

C#综合揭秘——细说多线程(下)

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