思路来源：http://bbs.csdn.NET/topics/390819824，引用该页面某网友提供的方法。
题目：我现在有100个任务，需要多线程去完成，但是要限定同时并发数量不能超过5个。
原理：初始启用5个线程，然后让线程中的过程执行完毕之后，自己去取下一个任务，启动下一个线程。
[csharp] view plain copy print ? public class MyTaskList { public List<Action> Tasks = new List<Action>(); public void Start() { for (var i = 0; i < 5; i++) StartAsync(); } public event Action Completed; public void StartAsync() { lock (Tasks) { if (Tasks.Count > 0) { var t = Tasks[Tasks.Count - 1]; Tasks.Remove(t); ThreadPool.QueueUserWorkItem(h => { t(); StartAsync(); }); } else if (Completed != null) Completed(); } } } public class MyTaskList { public List<Action> Tasks = new List<Action>(); public void Start() { for (var i = 0; i < 5; i++) StartAsync(); } public event Action Completed; public void StartAsync() { lock (Tasks) { if (Tasks.Count > 0) { var t = Tasks[Tasks.Count - 1]; Tasks.Remove(t); ThreadPool.QueueUserWorkItem(h => { t(); StartAsync(); }); } else if (Completed != null) Completed(); } } } 调用方式：
1，自动加入的100个测试任务，每一个运行时间都是不定的、随机的。2，这里的 StartAsync 方法瞬间就结束了，根本不会阻塞，也不会等待什么 while 循环结束
[csharp] view plain copy print ? var rnd = new Random(); var lst = new MyTaskList(); for (var i = 0; i < 100; i++) { var s = rnd.Next(10); var j = i; var 测试任务 = new Action(() => { Console.WriteLine(string.Format("第{0}个任务（用时{1}秒）已经开始", j, s)); Thread.Sleep(s * 1000); Console.WriteLine(string.Format("第{0}个任务（用时{1}秒）已经结束", j, s)); }); lst.Tasks.Add(测试任务); } lst.Completed += () => Console.WriteLine("____________________没有更多的任务了！"); lst.Start(); var rnd = new Random(); var lst = new MyTaskList(); for (var i = 0; i < 100; i++) { var s = rnd.Next(10); var j = i; var 测试任务 = new Action(() => { Console.WriteLine(string.Format("第{0}个任务（用时{1}秒）已经开始", j, s)); Thread.Sleep(s * 1000); Console.WriteLine(string.Format("第{0}个任务（用时{1}秒）已经结束", j, s)); }); lst.Tasks.Add(测试任务); } lst.Completed += () => Console.WriteLine("____________________没有更多的任务了！"); lst.Start();
自己使用到程序中，自定义最大线程数，然后循环启用最大线程数个线程执行任务，等待有线程完成，退出本次运行方法和线程前，再次调用启用线程方法调用下一个线程，依次循环，直至完成：
[csharp] view plain copy print ? AutoResetEvent[] waitEnents = new AutoResetEvent[n_max_thread]; for (int i = 0; i < n_max_thread; i++) { calcState.wait_event = waitEnents[i] = new AutoResetEvent(false); StartAsync(calcState); } AutoResetEvent.WaitAll(waitEnents); private static void StartAsync(CalcState calcState) { lock (calcState.locker_ListFormula) { if (calcState.lstFormula.Count > 0) { calcState.formulaAttr = calcState.lstFormula.ElementAt(calcState.lstFormula.Count - 1).Value; calcState.lstFormula.Remove(calcState.lstFormula.ElementAt(calcState.lstFormula.Count - 1).Key); ThreadPool.QueueUserWorkItem(new WaitCallback(ExecAsync), calcState); } else { calcState.wait_event.Set(); } } } private static void ExecAsync(object obj) { CalcState calcState = obj as CalcState; startCalcFormula(calcState); //递归处理下一个公式 StartAsync(calcState); } private static void startCalcFormula(CalcState calcState) { } AutoResetEvent[] waitEnents = new AutoResetEvent[n_max_thread]; for (int i = 0; i < n_max_thread; i++) { calcState.wait_event = waitEnents[i] = new AutoResetEvent(false); StartAsync(calcState); } AutoResetEvent.WaitAll(waitEnents); private static void StartAsync(CalcState calcState) { lock (calcState.locker_ListFormula) { if (calcState.lstFormula.Count > 0) { calcState.formulaAttr = calcState.lstFormula.ElementAt(calcState.lstFormula.Count - 1).Value; calcState.lstFormula.Remove(calcState.lstFormula.ElementAt(calcState.lstFormula.Count - 1).Key); ThreadPool.QueueUserWorkItem(new WaitCallback(ExecAsync), calcState); } else { calcState.wait_event.Set(); } } } private static void ExecAsync(object obj) { CalcState calcState = obj as CalcState; startCalcFormula(calcState); //递归处理下一个公式 StartAsync(calcState); } private static void startCalcFormula(CalcState calcState) { }
转载于:https://www.cnblogs.com/c-x-a/p/7428523.html
