C#线程池

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class Program{// 使用BeginXXX/EndXXX和IAsyncResult对象的方式被称为异步编程模型（APM模式）delegate string RunOnThreadPool(out int threadId);static void Main(string[] args){int threadId = 0;// 给委托变量赋值RunOnThreadPool poolDelegate = Test;var t = new Thread(() => { Test(out threadId); });t.Start();t.Join();Console.WriteLine($\"1.返回的线程Id：{threadId}\");// 通过调用委托变量的BeginInvoke方法来运行委托（执行Test方法）IAsyncResult ar = poolDelegate.BeginInvoke(out threadId, Callback, \"异步委托调用\");ar.AsyncWaitHandle.WaitOne();// 调用委托的EndInvoke会等待异步操作（Test方法）完成// 异步操作执行完成之后，开始执行回掉函数；异步操作和回掉函数很可能会被线程池中同一个工作线程执行string result = poolDelegate.EndInvoke(out threadId, ar);Console.WriteLine($\"2.返回的线程Id：{threadId}\");Console.WriteLine($\"返回值：{result}\");Console.ReadKey();}static void Callback(IAsyncResult ar){Console.WriteLine(\"开始执行回掉函数...\");Console.WriteLine($\"异步状态：{ar.AsyncState}\");Console.WriteLine($\"是否为线程池中的线程：{Thread.CurrentThread.IsThreadPoolThread}\");Console.WriteLine($\"线程池工作线程Id：{Thread.CurrentThread.ManagedThreadId}\");}static string Test(out int threadId){Console.WriteLine(\"开始测试方法...\");Console.WriteLine($\"是否为线程池中的线程：{Thread.CurrentThread.IsThreadPoolThread}\");Thread.Sleep(TimeSpan.FromSeconds(2));threadId = Thread.CurrentThread.ManagedThreadId;return $\"线程Id：{threadId}\";}}

1000

　　向线程池中放入异步操作

class Program{static void Main(string[] args){ThreadPool.QueueUserWorkItem(AsyncOperation);Thread.Sleep(TimeSpan.FromSeconds(2));ThreadPool.QueueUserWorkItem(AsyncOperation, \"async state\");Thread.Sleep(TimeSpan.FromSeconds(2));ThreadPool.QueueUserWorkItem(state =>{Console.WriteLine($\"操作状态：{state}\");Console.WriteLine($\"工作线程Id：{Thread.CurrentThread.ManagedThreadId}\");Thread.Sleep(TimeSpan.FromSeconds(2));}, \"lambda state\");const int x = 1;const int y = 2;const string lambdaState = \"lambda state 2\";// 使用闭包机制，无需传递lambda表达式的状态参数ThreadPool.QueueUserWorkItem(_ =>{Console.WriteLine($\"操作状态：{x + y},{lambdaState}\");Console.WriteLine($\"工作线程Id：{Thread.CurrentThread.ManagedThreadId}\");Thread.Sleep(TimeSpan.FromSeconds(2));});Console.ReadKey();}static void AsyncOperation(object state){Console.WriteLine($\"操作状态：{state ?? \"(null)\"}\");Console.WriteLine($\"工作线程Id：{Thread.CurrentThread.ManagedThreadId}\");Thread.Sleep(TimeSpan.FromSeconds(2));}}

　　线程池与并行度：