C# 在异步中使用HttpWebRequest出现的“正在终止线程”错误的解决方案

最近做接口对接，因需求变化需要用到异步推送信息，就利用委托做了异步。

程序运行过程中时不时出现“正在终止线程”的错误信息，导致两边订单信息不一致，代码如下：

　　　　　　　byte[] byteData = Encoding.UTF8.GetBytes(parameters);
            HttpWebResponse response=null;
            Stream myResponseStream = null;
            Stream myRequestStream = null;try
            {
                var request=(HttpWebRequest) WebRequest.Create(Url);
                request.Proxy = null;//不使用代理
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = byteData.Length;
                
                using (myRequestStream = request.GetRequestStream())
                {
                    myRequestStream.Write(byteData, 0, byteData.Length);
                }

                response = (HttpWebResponse) request.GetResponse();
                myResponseStream = response.GetResponseStream();
                //将响应流转成xml对象
                XmlDocument doc = new XmlDocument();
                if (myResponseStream != null)
                    doc.Load(myResponseStream);
                //返回xml对象
                return doc;
            }
            catch (Exception ex)
            {
                LogHelper.CreateLog("post信息时出错！信息：" + ex.Message, orderid, httpContext);
                return null;
            }
            finally
            {
                if (myResponseStream != null)
                {
                    myResponseStream.Close();
                    myResponseStream.Dispose();
                }
                if (response != null)
                {
                    response.Close();
                    response.Dispose();
                }
                if (myRequestStream != null)
                {
                    myRequestStream.Close();
                    myRequestStream.Dispose();
                }
            }

网上寻找解决方案，基本上都是Response.Redirect导致的错误。我的代码上面并没有这些玩意儿。。。

实在是无法组织语言了，归根到底的原因就是C#中使用多线程使用HttpWebRequest时，默认的连接数只有2。

然后有时候因为对方服务器的原因导致访问超时，如果没有做超时处理的话，request对象就不会被释放，后面便导致一系列的问题。

解决方法之一就是在调用HttpWebRequest对象之前将连接数改大。

System.Net.ServicePointManager.DefaultConnectionLimit = 24

解决后代码：

            byte[] byteData = Encoding.UTF8.GetBytes(parameters);
            HttpWebResponse response=null;
            Stream myResponseStream = null;
            Stream myRequestStream = null;
            System.Net.ServicePointManager.DefaultConnectionLimit = 24;
            try
            {
                var request=(HttpWebRequest) WebRequest.Create(Url);
                request.Proxy = null;//不使用代理
                request.KeepAlive = false;//不建立持久性连接
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = byteData.Length;
                
                using (myRequestStream = request.GetRequestStream())
                {
                    myRequestStream.Write(byteData, 0, byteData.Length);
                }

                response = (HttpWebResponse) request.GetResponse();
                myResponseStream = response.GetResponseStream();
                //将响应流转成xml对象
                XmlDocument doc = new XmlDocument();
                if (myResponseStream != null)
                    doc.Load(myResponseStream);
                //返回xml对象
                return doc;
            }
            catch (Exception ex)
            {
                LogHelper.CreateLog("post信息时出错！信息：" + ex.Message, orderid, httpContext);
                return null;
            }
            finally
            {
                if (myResponseStream != null)
                {
                    myResponseStream.Close();
                    myResponseStream.Dispose();
                }
                if (response != null)
                {
                    response.Close();
                    response.Dispose();
                }
                if (myRequestStream != null)
                {
                    myRequestStream.Close();
                    myRequestStream.Dispose();
                }
            }            

这个个数，有相关说法是CPU的数量*2，具体有待考证，不过已经解决了我的问题。

其他解决方式参考连接：

http://www.cnblogs.com/eaglet/archive/2012/05/18/2507179.html

http://www.cnblogs.com/1971ruru/archive/2012/04/11/2442589.html

http://blog.sina.com.cn/s/blog_3eea4f680100s48d.html