任务时间较长，且单个任务执行时间不一致的情况下多线程分配
对于开发人员来说遇到多线程问题是十分常见的，一般处理方式是简单粗暴直接开N的线程然后把任务分为N组。这种处理方式有一个明显的弊端就是每个分组执行时间不一定一致，这样会导致线程空闲的状态。
下文中很多地方提到线程不是指技术上的而是逻辑上的。
第一步：
在构造器中初始化信息：
_reqsBusy：忙碌信息，_workingSignals：工作线程信息，_reqCount：线程数，list：待执行列表，cList：执行完成列表
public class ExtensionTaskFactory<T> { private bool[] _reqsBusy = null; private bool[] _workingSignals = null; private int _reqCount = 4; private List<T> list; private List<T> cList = new List<T>(); private Timer _checkTimer; public bool IsFinish; private DateTime _createTime; public ExtensionTaskFactory(List<T> l) { list = l; _reqsBusy = new bool[_reqCount]; _workingSignals = new bool[_reqCount]; for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } _createTime = DateTime.Now; } public ExtensionTaskFactory(List<T> l, int count) { list = l; _reqCount = count; _reqsBusy = new bool[_reqCount]; _workingSignals = new bool[_reqCount]; for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } _createTime = DateTime.Now; } }
第二步：
开始任务（Start()）-> 队空闲线程派发任务（DispatchWork()） -> 任务派发后修改当前线程状态,并且执行相关任务逻辑 (Process(int i)) -> 任务执行完成后再次请求派发任务
private async void Process(int i) { _reqsBusy[i] = true; #region Adjust queue if (list.Count() > 0) { Console.WriteLine("Remaining {0} data need to be executed.", list.Count()); T model = list.FirstOrDefault(); list.Remove(model); cList.Add(model); await Dotaskfunction(model); } else { _workingSignals[i] = false; _reqsBusy[i] = false; return; } #endregion _reqsBusy[i] = false; DispatchWork(); } private void DispatchWork() { for (int i = 0; i < _reqCount; i++) { if (!_reqsBusy[i]) { Process(i); } } } private async Task Dotaskfunction(T model) { await Task.Run(() => { //Do someThing }); } public void Start() { DispatchWork(); }
第三步：将任务逻辑以事件形式注入到 Dotaskfunction 中
- 定义事件
public event TaskEventHandler<T> TaskEvent;
- 修改 Dotaskfunction
private async Task Dotaskfunction(T model) { await Task.Run(() => { //Console.WriteLine("task {0} has been started!", s); //Do someThing if (TaskEvent != null) { TaskEvent(model, _createTime); } //Thread.Sleep(3000); //Console.WriteLine("task {0} has been done!", s); }); }
第四步：
监测任务完成情况
- 监测任务线程是否都已经闲置
private void CheckFinish(object param) { if (IsFinished()) { _checkTimer.Dispose(); //Stop Timer _checkTimer = null; IsFinish = true; Console.WriteLine("Async Task End !"); Console.WriteLine("-------------------" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + "-------------------"); } } private bool IsFinished() { bool result = false; for (int i = 0; i < _workingSignals.Count(); i++) { if (_workingSignals[i]) { break; } if (i == _workingSignals.Count() - 1) { result = true; } } return result; }
- 修改 Start() 方法，注册Timer定时检测任务是否完成
public void Start() { _checkTimer = new Timer(new TimerCallback(CheckFinish), null, 0, 3000); DispatchWork(); }
第五步：辅助功能
- 添加任务
public void AddList(List<T> addlist) { list.AddRange(addlist); }
- 重新启动任务
public void Restart() { if (_checkTimer == null) { _checkTimer = new Timer(new TimerCallback(CheckFinish), null, 0, 3000); } for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } DispatchWork(); }
- 获取已完成任务
public List<T> GetResult() { return cList; }
第六步：调用示例
- 调用
List<Test> tasks;
ExtensionTaskFactory<Test> task = new ExtensionTaskFactory<Test>(tasks, 4); task.TaskEvent += Task_RunQueryEvent; task.Start(); - 注册任务处理逻辑事件
private void Task_RunQueryEvent(RunQueryLog log, DateTime time) { //Do something }
最后附上源码
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; using System.Threading.Tasks; namespace NewsletterAlert.Core.Common { public delegate void TaskEventHandler<T>(T model, DateTime time); public class ExtensionTaskFactory<T> { private bool[] _reqsBusy = null; private bool[] _workingSignals = null; private int _reqCount = 4; private List<T> list; private List<T> cList = new List<T>(); private Timer _checkTimer; public bool IsFinish; private DateTime _createTime; public event TaskEventHandler<T> TaskEvent; public ExtensionTaskFactory(List<T> l) { list = l; _reqsBusy = new bool[_reqCount]; _workingSignals = new bool[_reqCount]; for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } _createTime = DateTime.Now; } public ExtensionTaskFactory(List<T> l, int count) { list = l; _reqCount = count; _reqsBusy = new bool[_reqCount]; _workingSignals = new bool[_reqCount]; for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } _createTime = DateTime.Now; } private async void Process(int i) { _reqsBusy[i] = true; #region Adjust queue if (list.Count() > 0) { Console.WriteLine("Remaining {0} data need to be executed.", list.Count()); T model = list.FirstOrDefault(); list.Remove(model); cList.Add(model); await Dotaskfunction(model); } else { _workingSignals[i] = false; _reqsBusy[i] = false; return; } #endregion _reqsBusy[i] = false; DispatchWork(); } private void DispatchWork() { for (int i = 0; i < _reqCount; i++) { if (!_reqsBusy[i]) { Process(i); } } } private async Task Dotaskfunction(T model) { await Task.Run(() => { //Console.WriteLine("task {0} has been started!", s); //Do someThing if (TaskEvent != null) { TaskEvent(model, _createTime); } //Thread.Sleep(3000); //Console.WriteLine("task {0} has been done!", s); }); } public void Start() { _checkTimer = new Timer(new TimerCallback(CheckFinish), null, 0, 3000); DispatchWork(); } private void CheckFinish(object param) { if (IsFinished()) { _checkTimer.Dispose(); //Stop Timer _checkTimer = null; IsFinish = true; Console.WriteLine("Async Task End !"); Console.WriteLine("-------------------" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + "-------------------"); } } private bool IsFinished() { bool result = false; for (int i = 0; i < _workingSignals.Count(); i++) { if (_workingSignals[i]) { break; } if (i == _workingSignals.Count() - 1) { result = true; } } return result; } public void AddList(List<T> addlist) { list.AddRange(addlist); } public void Restart() { if (_checkTimer == null) { _checkTimer = new Timer(new TimerCallback(CheckFinish), null, 0, 3000); } for (int i = 0; i < _workingSignals.Count(); i++) { _workingSignals[i] = true; } DispatchWork(); } public List<T> GetResult() { return cList; } } }
