C#中，提交对应的POST类型http请求之前，会执行：

Stream postDataStream = req.GetRequestStream();

然后填充对应的post数据，再提交http的请求。

但是调试的时候，发现每次执行GetRequestStream都很慢。

慢也就算了，结果最近发现，某次，执行req.GetRequestStream();死掉。

【解决过程】

1.网上找了找，根据 GetRequestStream的效率为什么这么低？ 的解释，说是.NET每次会自动搜索代理，所以很慢，此处没有设置代理的话，应该直接复制为空：

req.Proxy = null;

然后再去执行GetRequestStream，这样就不会慢了。

然后去试了试，好像是这个效果。

2.结果第二天同样的代码，去调试，结果GetRequestStream的地方，还是死掉了。

原因暂未知。

3.后来的情况是，，同样的代码，再次运行，就不死了，虽然也还是有时候效率低，反应慢，但是不会死了。具体根本原因，感觉还是没有找到。

4. 后来的多次调试，发现对于：

req.Proxy = null;

好像也没啥效果。

只是碰巧找到了，关于设置proxy为null的原始的官方的解释：

”C# 3.0 in a Nutshell, Third Edition: A Desktop Quick Reference“的Chapter 14. Networking：

Warning

If you don’t have a proxy, you must set the Proxy property to null on all WebClient and WebRequest objects. Otherwise, the Framework may attempt to "auto-detect" your proxy settings, adding up to 30 seconds to your request. If you’re wondering why your web requests execute slowly, this is probably it!

 

但是此处，对于我所遇到的，执行GetRequestStream会死掉的问题，还是没有啥帮助。

5.多次调试得到的结果是,如果是对于:

Stream postDataStream = req.GetRequestStream();

是单步调试的话,好像很少会死掉.

而如果直接运行,没有打断点,那么经常容易死掉.

6.参考：GetRequestStream throws Timeout exception randomly，去试了：

using (Stream postDataStream = req.GetRequestStream()) { postDataStream.Write(postBytes, 0, postBytes.Length); postDataStream.Close(); }

还是会死掉。

7.网上看到：HttpWebRequest.GetRequestStream() hangs，看起来此问题，好像已经是官方承认的一个bug。

不过即使真的是bug，其解释说是在.NET 4.0 beta2才解决掉，而我此处无法用.NET 4.0，只能用.NET 2.0/3.0/3.5，所以，如果真是bug的话，那就真的悲剧了。。。

还是先去看看，有没有其他解决办法再说吧。

8.试了如下代码：

try { Stream postDataStream = req.GetRequestStream(); postDataStream.Write(postBytes, 0, postBytes.Length); postDataStream.Close(); } catch (WebException ex) { MessageBox.Show(ex.Message); }

单步调试了：

Stream postDataStream = req.GetRequestStream();

发现经过很长的时间之后，捕获到了异常WebException ex，出现了“Unable to connect to the remote server”错误，其详细信息如下：

ex {"Unable to connect to the remote server"} System.Net.WebException base {"Unable to connect to the remote server"} System.InvalidOperationException {System.Net.WebException} base {"Unable to connect to the remote server"} System.SystemException {System.Net.WebException} base {"Unable to connect to the remote server"} System.Exception {System.Net.WebException} _className null string _data null System.Collections.IDictionary _dynamicMethods null object _exceptionMethod null System.Reflection.MethodBase _exceptionMethodString null string _helpURL null string _HResult -2146233079 int _innerException {"A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 65.55.254.42:443"} System.Exception {System.Net.Sockets.SocketException} _message "Unable to connect to the remote server" string _remoteStackIndex 0 int _remoteStackTraceString null string _source null string _stackTrace {sbyte[96]} object {sbyte[]} _stackTraceString null string _xcode -532459699 int _xptrs 0 System.IntPtr Data {System.Collections.ListDictionaryInternal} System.Collections.IDictionary {System.Collections.ListDictionaryInternal} HelpLink null string HResult -2146233079 int InnerException {"A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 65.55.254.42:443"} System.Exception {System.Net.Sockets.SocketException} IsTransient false bool Message "Unable to connect to the remote server" string Source "System" string StackTrace " at System.Net.HttpWebRequest.GetRequestStream(TransportContext& context)\r\n at System.Net.HttpWebRequest.GetRequestStream()\r\n at InsertSkydriveFiles.skydrive.beforeUploadFile()" string TargetSite {System.IO.Stream GetRequestStream(System.Net.TransportContext ByRef)} System.Reflection.MethodBase {System.Reflection.RuntimeMethodInfo} Static members InternalStatus ServicePointFatal System.Net.WebExceptionInternalStatus m_InternalStatus ServicePointFatal System.Net.WebExceptionInternalStatus m_Response null System.Net.WebResponse m_Status ConnectFailure System.Net.WebExceptionStatus Response null System.Net.WebResponse Status ConnectFailure System.Net.WebExceptionStatus