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http://www.cnblogs.com/Charltsing/p/publisher.html
最近测试task并发任务的效率与线程池的区别,发现了另外一个问题。task建立任务的速度很快,输出到UI的信息过频,导致UI假死。
private void TestMakeTasks(object obj) { string msg = ""; //循环创建task for (int i = 0; i < 3000; i++) { //主线程(winform)--子线程(Thread)--工作线程(task) //不能在循环里面连续访问UI,会造成UI来不及处理,导致假死。 Task<string> tt = Task.Factory.StartNew<string>(test, i); tt.ContinueWith((t) => { if (t.IsFaulted) { string msgexcep = (string.Format("I have observed a {0}", t.Exception.InnerException.GetType().Name)); Interlocked.Increment(ref responsecount); Interlocked.Decrement(ref threadscount); } }); //Thread.Sleep(1); //避免过快发送UI更新请求,导致假死。 msg = " 已发送请求数:" + requestcount.ToString() + " 已完成请求数:" + responsecount.ToString(); //输出线程建立信息给UI,过频会导致假死。
PublishStatus(msg); Interlocked.Increment(ref threadscount); Interlocked.Increment(ref requestcount); if (_isStop) { PublishMessage("正在退出...\r\n"); break; } } PublishMessage("发送完毕,请等待线程运行完毕!\r\n"); while (responsecount < requestcount) { Thread.Sleep(300); msg = "!已发送请求数:" + requestcount.ToString() + " 已完成请求数:" + responsecount.ToString(); PublishStatus(msg); } _isRunning = false; PublishMessage("\r\n全部线程运行完毕!\r\n"); }
为了解决这个问题,考虑使用publisher模式控制UI输出
public class Publisher { public bool isbusy = false; //标志 public delegate void PublishEventHander(object sender, PubEventArgs e); public event PublishEventHander PublishMessage; public event PublishEventHander PublishStatus; //声明一个可重写的OnPublish的保护函数 protected virtual void OnPublishMessage(PubEventArgs e) { if (PublishMessage != null) { //Sender = this,也就是Publisher this.PublishMessage(this, e); } } protected virtual void OnPublishStatus(PubEventArgs e) { if (PublishStatus != null) { //Sender = this,也就是Publisher this.PublishStatus(this, e); } } /// <summary> /// 触发publish message事件 /// </summary> public void IssueMessage(string message) { OnPublishMessage(new PubEventArgs(message)); } /// <summary> /// 触发publish status事件 /// </summary> public void IssueStatus(string message) { if (!isbusy) OnPublishStatus(new PubEventArgs(message)); } }
同时,在UI输出部分,使用Invoke来阻止更多的UI操作(不能使用BeginInvoke)。
private void WriteStatus(string msg) { if (this.lblStatus.InvokeRequired) { Invoke(cdWriteStatus, msg); } else { UpdatelblMethod(msg); } }
大致思路是 task创立任务之后,发给publisher一个通知(使用IssueStatus函数),publisher通过OnPublishStatus事件通知给Subscriber,UI界面作为订阅者通过设置publisher的busy状态使得publisher取消后面多余的输出事件。
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使用publisher模式控制频繁的UI输出,避免Winform界面假死
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原文地址:http://www.cnblogs.com/Charltsing/p/publisher.html