Httpwebrequest后调用超时不起作用

Question

当IP正确时，我看不到任何问题，但当IP关闭时，超时值不起作用，需要75秒或80秒才能超时。。。。。没有代理的相同代码可以在15秒内超时，这是我设置的值。

这是代理级别限制还是任何编码问题。。。我对此做了很多研究，并尝试了谷歌的很多东西，但都无济于事。。

这是我的代码

{
HttpWebRequest ObjHttpWebRequest = null;
HttpWebResponse objHttpWebResponse = null;
Stopwatch watch = new Stopwatch();
string strReturn = string.Empty;
string validUrl = "false";
try
{
watch.Start();
string DATA = "postdata";
ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(MyCertValidationCb);
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
ObjHttpWebRequest = (HttpWebRequest)WebRequest.Create("https://196.234.502.247:4510/path");
ObjHttpWebRequest.Timeout = 15000;
ObjHttpWebRequest.Method = "POST";
ObjHttpWebRequest.ContentType = "application/json";
ObjHttpWebRequest.ContentLength = DATA.Length;
{
WebProxy proxy = new WebProxy();
proxy.Address = new Uri("http://proxy.com");
proxy.UseDefaultCredentials = true;
ObjHttpWebRequest.Proxy = proxy;
}
X509Certificate2 X509cert2_client = new X509Certificate2(HttpContext.Current.Request.PhysicalApplicationPath + @"foldertest.pfx", "test");
ObjHttpWebRequest.ClientCertificates.Add(X509cert2_client);
byte[] byteArray = Encoding.UTF8.GetBytes(DATA);
ObjHttpWebRequest.ContentLength = byteArray.Length;
Stream objRequestStream = ObjHttpWebRequest.GetRequestStream();
objRequestStream.Write(byteArray, 0, byteArray.Length);
objRequestStream.Close();
using (objHttpWebResponse = ObjHttpWebRequest.GetResponse() as HttpWebResponse)
{
using (var objResponseStream = objHttpWebResponse.GetResponseStream())
{
using (var objResponseStreamReader = new StreamReader(objResponseStream, Encoding.UTF8))
{
strReturn = objResponseStreamReader.ReadToEnd();
objResponseStreamReader.Close();
}
objResponseStream.Close();
}
objHttpWebResponse.Close();
}
}
catch (Exception ex)
{
HttpContext.Current.Response.Write(ex.Message);
}
finally
{
watch.Stop();
if (ObjHttpWebRequest != null) ObjHttpWebRequest.Abort();
if (objHttpWebResponse != null) objHttpWebResponse.Close();
HttpContext.Current.Response.Write(strReturn+ "--"+ watch.Elapsed.TotalSeconds.ToString()+"__"+ validUrl);
}
}

Answer 1

根据MSDN文档，使用主机名可能会导致超时问题：

域名系统(DNS(查询可能需要长达15秒的时间才能返回或超时。如果您的请求包含需要解析的主机名，并且您将Timeout设置为小于15秒的值，则可能需要15秒或更长时间才能引发WebException来指示请求超时。

我不确定这是否是最初的问题，我会尝试以任何一种方式识别它，但您仍然可以自己实现超时以使其工作：

byte[] byteArray = Encoding.UTF8.GetBytes(DATA);
ObjHttpWebRequest.ContentLength = byteArray.Length;
var cancelSource = new CancellationTokenSource();
var requestHandlingTask = DoRequestHandling(ObjHttpWebRequest, byteArray, cancelSource.Token);
if (await Task.WhenAny(requestHandlingTask, Task.Delay(TIMEOUT)) == requestHandlingTask)
{
// The task completed inside the timeout
strReturn = requestHandlingTask.Result;
}
else
{
// Timeout handling
cancelSource.Cancel();
// ...
}

在请求处理中，只要有可能(方法调用仍将运行更长时间(，我们就会根据取消令牌进行检查，并在主逻辑已经可以在另一个线程上继续时取消其余操作。

static async Task<string> DoRequestHandling(HttpWebRequest request, byte[] arrByteData, CancellationToken cancelToken)
{
string strReturn = String.Empty;
var requestStream = await request.GetRequestStreamAsync()
.ConfigureAwait(false);
if (!cancelToken.IsCancellationRequested)
{
requestStream.Write(arrByteData, 0, arrByteData.Length);
requestStream.Close();
if (!cancelToken.IsCancellationRequested)
{
using (var response = await request.GetResponseAsync().ConfigureAwait(false) as HttpWebResponse)
using (var responseStream = response.GetResponseStream())
using (var responseStreamReader = new StreamReader(responseStream, Encoding.UTF8))
{
strReturn = await responseStreamReader.ReadToEndAsync()
.ConfigureAwait(false);
}
}
else
{
// Request was cancelled -> exit
}
}
else
{
// Request was cancelled -> exit
}
return strReturn;
}