C#使用semaphore来管理异步下载请求的方法

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。