本文实例讲述了C#使用semaphore来管理异步下载请求的方法。分享给大家供大家参考。具体实现方法如下：

var semaphor = new Semaphore(50, 50); // We allow at most 50 threads for crawling var resultPins = new List<Pin>(); // Results stored here foreach (var pin in new HashSet<string>(pinIdList)) { semaphor.WaitOne(); Console.Write(">"); var pinClient = new WebClient(); pinClient.DownloadStringCompleted += (sender, ex) => { var html = ex.Result.Replace("n", ""); pinClient.Dispose(); lock (pinIdList) { // do some post-processing and write back the results } Console.Write("<"); semaphor.Release(); }; pinClient.DownloadStringAsync(new Uri(string.Format("http://pinterest.com/pin/{0}/", pin))); } for (int i = 0; i < 50; i++) semaphor.WaitOne(); // Wait until the last thread ends. semaphor.Dispose(); Console.WriteLine();

希望本文所述对大家的C#程序设计有所帮助。