HttpWebRequest中GetResponse或者說GetRequestStream偶爾超時，或者是各種操作超時造成的假死的一些解決方案

今天用了將近一天的時間來查找這個問題的存在，不停的百度查找原因測試原因，發現解決方案很是簡單，不過最好還好哦啊都解決了，在這裡紀錄一下，希望可以幫到你們

 payload = System.Text.Encoding.UTF8.GetBytes(postDataStr);
                request.ContentLength = payload.Length;
                Stream writer = request.GetRequestStream();
                writer.Write(payload, 0, payload.Length);
                //writer.Flush();
                writer.Close();
                //HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                HttpWebResponse res;
                try
                {
                    System.Net.ServicePointManager.DefaultConnectionLimit = 200;
                    res = (HttpWebResponse)request.GetResponse();
                }
                catch (WebException ex)
                {

                    res = (HttpWebResponse)ex.Response;
                }

 今天我的res 一直報操作超時，百度了很多方案，一一測試，總結來說，如果你也出現了這種錯誤，可以一次嘗試一下方案

第一種：加長request的timeout的時間，預設是100秒（我就是測試了好多方案，才發現我的timeout的時間太短，引起的操作超時）

第二種：設置request.KeepAlive = false;原因是：預設KeepAlive的屬性是true，將此屬性設置為 true 以發送帶有 Keep-alive 值的 Connection HTTP 標頭。 應用程式使用 KeepAlive 指示持久連接的首選項。 當 KeepAlive 屬性為 true 時，應用程式與支持它們的伺服器建立持久連接。也要記住要及時關閉相對應的關閉工作

if (request != null)
                {
                    request.Abort();
                }
                if (res != null)
                {
                    res.Close();
                }

第三種：

System.Net.ServicePointManager.DefaultConnectionLimit = 200;

 加上這句話，因為這個預設設置的是2，當http的連接超過2條時，也會報這種操作超時的錯誤

第四種：

                System.GC.Collect();
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = postDataStr.Length;
                request.KeepAlive = false;
                request.Timeout = 6000000;

 在

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);

 之前加上：System.GC.Collect();

原因是：系統中的http相關的資源沒有正確的釋放，導致後續的GetResponse或者說GetRequestStream超時死掉

    改進之後的所有代碼：

public static bool HttpPost(string Url, string postDataStr, out string errMsg, out string returnData)
        {
            try
            {
                System.GC.Collect();
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = postDataStr.Length;
                request.KeepAlive = false;
                request.Timeout = 6000000;
                //StreamWriter writer = new StreamWriter(request.GetRequestStream(), Encoding.UTF8);
                //writer.Write(postDataStr);
                //writer.Flush();
                byte[] payload;
                payload = System.Text.Encoding.UTF8.GetBytes(postDataStr);
                request.ContentLength = payload.Length;
                Stream writer = request.GetRequestStream();
                writer.Write(payload, 0, payload.Length);
                //writer.Flush();
                writer.Close();
                //HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                HttpWebResponse res;
                try
                {
                    System.Net.ServicePointManager.DefaultConnectionLimit = 200;
                    res = (HttpWebResponse)request.GetResponse();
                }
                catch (WebException ex)
                {

                    res = (HttpWebResponse)ex.Response;
                }
                
              
                //StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                StreamReader reader = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
                string retString = reader.ReadToEnd();
                errMsg = "";
                try
                {
                    returnData = Util.base642Str(retString);
                }
                catch (Exception)
                {
                    returnData = retString;
                    //throw;
                }
                if (request != null)
                {
                    request.Abort();
                }
                if (res != null)
                {
                    res.Close();
                }
                return true;
            }

                       參考文章：https://www.cnblogs.com/wohexiaocai/p/5673193.html