HttpWebRequest.GetResponse()随机挂起

Question

我有以下代码：

public static QHttpResponse Execute(QHttpRequest request)
{
    //Setup the request
    HttpWebRequest webrequest = (HttpWebRequest) WebRequest.Create(request.GetFinalUrl());
    webrequest.AllowAutoRedirect = request.IsAllowRedirects;
    webrequest.Method = request.Method;
    webrequest.Accept = "application/json, text/javascript;q=0.9, */*;q=0.5";
    webrequest.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
    //request.Host is set automatically
    webrequest.UserAgent = request.UserAgent;
    if (!String.IsNullOrEmpty(request.Referrer))
        webrequest.Referer = request.Referrer;
    webrequest.Timeout = 50000;
    webrequest.KeepAlive = false;
    webrequest.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.Revalidate);
    webrequest.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
    if (request.IsAjax)
    {
        webrequest.Headers.Add("X-Request", "JSON");
        webrequest.Headers.Add("X-Requested-With", "XMLHttpRequest");
        webrequest.Headers.Add("X-Prototype-Version", "1.7");
    }

    // Cookies
    webrequest.CookieContainer = request.Cookies;

    // Write the data to the body for POST and other methods
    if (request.IsMethodPost())
    {
        byte[] dataBytes = Encoding.UTF8.GetBytes(request.GetDataParamString());
        webrequest.ContentLength = dataBytes.Length;

        using (Stream requestStream = webrequest.GetRequestStream())
            requestStream.Write(dataBytes, 0, dataBytes.Length);
    }

    // Get the response
    HttpWebResponse webresponse;
    try
    {
        webresponse = webrequest.GetResponse() as HttpWebResponse;
    }
    catch (WebException wex)
    {
        if(request.IsBypassError)
            webresponse = wex.Response as HttpWebResponse;
        else
            throw;
    }

    // Read to QHttpResponse object
    QHttpResponse response = new QHttpResponse();
    response.StatusCode = webresponse.StatusCode;
    response.NewCookies = webresponse.Cookies;
    using (Stream responseStream = webresponse.GetResponseStream())
        using (StreamReader reader = new StreamReader(responseStream))
            response.Reply = reader.ReadToEnd();

    webresponse.Close();

    return response;
}

我让这个代码从不同的位置运行多次，随机地(每隔几个小时)，它挂在下面一行：

webresponse = webrequest.GetResponse() as HttpWebResponse;

我尝试设置webrequest.KeepAlive = false;，但是我继续收到错误。

在解决这个问题上，我想要任何有帮助的人，谢谢。

编辑：我想补充一下，这段代码是从两个线程执行的。有时，它们可能连接到同一个主机，但只能从这两个线程连接。而且，正如我所看到的，响应是适当关闭的。

编辑2：Visual的调试器表示执行在System.dll!System.Net.Sockets.Socket.Receive上确实是卡住了。

编辑3：为了查看究竟是什么导致了错误，我将“获取响应”代码从上面修改为

// Get the response
HttpWebResponse webresponse = null;
try
{
    webresponse = webrequest.GetResponse() as HttpWebResponse;
}
catch (WebException wex)
{
    Console.WriteLine("Time : " + DateTime.Now);
    Console.WriteLine("Thread name : " + Thread.CurrentThread.Name);
    Console.WriteLine("Exception : " + wex);
    Console.WriteLine("Exc msg : " + wex.Message);
    Console.WriteLine("Url : " + request.GetFinalUrl());

    if (request.IsBypassError)
        webresponse = wex.Response as HttpWebResponse;
    else
    {
        if (webresponse != null)
        {
            webresponse.Close();
            webresponse.Dispose();
        }

        throw;
    }
}

我收到了这个输出：

Time : 5/11/2015 3:13:35 AM 
Thread name : BOT A
Exception : System.Net.WebException: The remote server returned an error: (500) Internal Server Error.
at System.Net.HttpWebRequest.GetResponse()
at Gameloop.Util.Web.QWebClient.Execute(QHttpRequest request) in e:\Visual Studio - Workspace\Gameloop.Util\Gameloop.Util\Web\QWebClient.cs:line 52 
Exc msg : The remote server returned an error: (500) Internal Server Error. 
Url : https://website1.com/url/path/to/something (I changed this)

这是唯一显示的错误，并遇到线程"BOT A“。然而，这并不是线程实际冻结的url。"BOT A“实际上是在晚上12点在website2.com被冻结的，而"BOT B”实际上是在早上7:00在website3.com被冻结的。我怀疑绞刑与例外情况有很大关系，因为在实际挂起之前，这些请求会被提出很多次。

Answer 1

我的第一个倾向是，您可能需要释放您的HttpWebResponse。通常，您可能会将其包装在一个using块中，但是由于您有两个可能分配webresponse的位置，所以您可能只想显式地释放它，如下所示。

webresponse.Close();
webresponse.Dispose();

我会从那里开始。

Answer 2

只需在try块中添加以下内容：

httpWReq.Timeout = 3000;