C#HttpWebRequest在两次服务器错误后超时

在我发出两个因“（500）内部服务器错误500）而引发异常的C#HttpWebRequests之后，第三次尝试引发超时异常。为什么它不抛出另一个（500）内部服务器错误异常

当我重新启动应用程序时，它抛出两个500错误，然后再次开始超时

这是我的代码：

GetPages GetPages = new GetPages();
string test = GetPages.GetPage(); /* Exception: (500) Internal Server Error */
GetPages.Dispose();

GetPages GetPages = new GetPages();
string test = GetPages.GetPage();  /* Exception: (500) Internal Server Error */
GetPages.Dispose();

GetPages GetPages = new GetPages();
string test = GetPages.GetPage();  /* Exception: time out, why? */
GetPages.Dispose();

namespace MyNamespace
{
    class GetPages
    {
        public string GetPage()
        {
            this.httpRequest = (HttpWebRequest)WebRequest.Create("http://myurl");

            try
            {
                StringBuilder postData = new StringBuilder(100);
                postData.Append("test=test");
                byte[] dataArray = Encoding.UTF8.GetBytes(postData.ToString());

                httpRequest.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
                httpRequest.KeepAlive = false;
                httpRequest.Proxy = null;
                httpRequest.Method = "POST";
                httpRequest.Timeout = 10;
                httpRequest.ContentType = "application/x-www-form-urlencoded";

                httpRequest.ContentLength = dataArray.Length;

                using (this.requestStream = httpRequest.GetRequestStream())
                {
                    requestStream.Write(dataArray, 0, dataArray.Length);
                    requestStream.Flush();
                    requestStream.Close();

                    this.webResponse = (HttpWebResponse)httpRequest.GetResponse();

                    Stream responseStream = webResponse.GetResponseStream();
                    StreamReader responseReader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                    String responseString = responseReader.ReadToEnd();


                    MessageBox.Show(responseString);
                    return responseString;
                }
            }

            catch (Exception e)
            {
                MessageBox.Show(e.Message);
                return "FAIL";
            }
        }

        public void Dispose()
        {
            System.GC.SuppressFinalize(this);
        }
    }
}

这是GetPage类和GetPage方法：

GetPages GetPages = new GetPages();
string test = GetPages.GetPage(); /* Exception: (500) Internal Server Error */
GetPages.Dispose();

GetPages GetPages = new GetPages();
string test = GetPages.GetPage();  /* Exception: (500) Internal Server Error */
GetPages.Dispose();

GetPages GetPages = new GetPages();
string test = GetPages.GetPage();  /* Exception: time out, why? */
GetPages.Dispose();

namespace MyNamespace
{
    class GetPages
    {
        public string GetPage()
        {
            this.httpRequest = (HttpWebRequest)WebRequest.Create("http://myurl");

            try
            {
                StringBuilder postData = new StringBuilder(100);
                postData.Append("test=test");
                byte[] dataArray = Encoding.UTF8.GetBytes(postData.ToString());

                httpRequest.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
                httpRequest.KeepAlive = false;
                httpRequest.Proxy = null;
                httpRequest.Method = "POST";
                httpRequest.Timeout = 10;
                httpRequest.ContentType = "application/x-www-form-urlencoded";

                httpRequest.ContentLength = dataArray.Length;

                using (this.requestStream = httpRequest.GetRequestStream())
                {
                    requestStream.Write(dataArray, 0, dataArray.Length);
                    requestStream.Flush();
                    requestStream.Close();

                    this.webResponse = (HttpWebResponse)httpRequest.GetResponse();

                    Stream responseStream = webResponse.GetResponseStream();
                    StreamReader responseReader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                    String responseString = responseReader.ReadToEnd();


                    MessageBox.Show(responseString);
                    return responseString;
                }
            }

            catch (Exception e)
            {
                MessageBox.Show(e.Message);
                return "FAIL";
            }
        }

        public void Dispose()
        {
            System.GC.SuppressFinalize(this);
        }
    }
}

更新

谢谢大家的帮助。我没能解决这个问题

dispose方法现在已不存在

我已将HttpWebRequest httpRequest、HttpWebResponse webResponse和Stream requestStream设置为本地，并使用以下using语句：

using (webResponse = (HttpWebResponse)httpRequest.GetResponse())
{
    using (Stream responseStream = webResponse.GetResponseStream())
    {
        using (StreamReader responseReader = new System.IO.StreamReader(responseStream, Encoding.UTF8))
        {
            responseString = responseReader.ReadToEnd();
        }
    }
}

另一次更新

这就是现在的整个GetPage方法：

public string GetPage()
{
    HttpWebRequest httpRequest;
    HttpWebResponse webResponse;
    Stream requestStream;

    try
    {
        StringBuilder postData = new StringBuilder(100);
        postData.Append("test=test");
        byte[] dataArray = Encoding.UTF8.GetBytes(postData.ToString());

        httpRequest = (HttpWebRequest)WebRequest.Create("http://myurl");

        httpRequest.Proxy = null;
        httpRequest.Method = "POST";
        httpRequest.Timeout = 10;
        httpRequest.ContentType = "application/x-www-form-urlencoded";

        httpRequest.ContentLength = dataArray.Length;

        using (requestStream = httpRequest.GetRequestStream())
        {
            /* this is never reached when the time out exception starts 
            so the error seems to be related to too many GetRequestStreams */

            requestStream.Write(dataArray, 0, dataArray.Length);

            webResponse = (HttpWebResponse)httpRequest.GetResponse();

            /* this is never reached when the 500 server error occurs */

            String responseString = "";
            using (Stream responseStream = webResponse.GetResponseStream())
            {
                using (StreamReader responseReader = new System.IO.StreamReader(responseStream, Encoding.UTF8))
                {
                    responseString = responseReader.ReadToEnd();
                    return responseString;
                }
            }
        }
    }

    catch (Exception e)
    {
        return "FAIL";
    }

    return "...";
}

**解决了** httpRequest没有得到abort（）'ed。在catch（）块中，我添加了httpRequest.abort（），现在它工作正常。

我怀疑这就是问题所在：

this.webResponse = (HttpWebResponse)httpRequest.GetResponse();
Stream responseStream = webResponse.GetResponseStream();
StreamReader responseReader = new StreamReader(responseStream, Encoding.UTF8);
String responseString = responseReader.ReadToEnd();

你不能处理这些一次性物品。这意味着到web服务器的连接将一直保持到完成，因此连接池（每台服务器有两个连接）将不允许任何其他请求

我建议：

• 将

  GetResponse

  调用移出请求流的using语句
• 您删除了对请求流的

  Flush

  和

  Close

  的显式调用（处理它就足够了）
• 您可以使用

  webResponse

  和

  webRequest

  局部变量而不是实例变量，除非以后确实需要它们，在这种情况下，您应该在

  dispose

  方法中处理它们
• 对于

  WebResponse

  、

  Stream

  和

  StreamReader

  使用

  语句。（严格来说，最后一个并不是必需的，因为处理流已经足够好了。）

• 您使

  GetPages

  无法实现

  IDisposable

  ，除非您确实需要它

---

HTTP协议定义同一服务器在同一时间只能建立两个连接。阅读成功或不成功后，关闭

responseStream

。

该Dispose方法是我见过的最糟糕的方法。进行这些更改后，您看到了什么行为？完全一样？是的，完全一样。你不认为这是他的处置方法吗？：）@科恩：嗯。。。这让我感到惊讶。可能是因为抛出了异常，所以无法处理响应。您可能会捕获WebException并在其中处理响应。。。但是如果你真的要这么做，那就太可怕了：（@jon:你能看看整个方法吗？（我在第一篇文章中又添加了一个更新）@koen:我没发现你把keep alive关掉了。好奇者和好奇者。我恐怕现在没有时间去复制它：（@jon:我不得不使用catch块中的abort（）方法手动中止httpRequest。非常感谢您的时间。我现在已经将responseStream包装在using语句中（请参阅第一篇文章中的更新）.够了吗？是的，我想这就是连接松动而没有关闭的地方。奇怪的是，我把responseStream放到了using block，仍然超时。