向主机发送大量请求时，System.Net.HttpWebRequest.GetResponse() 操作超时

我正在向具有不同数据的特定 Web 服务发送大量同时请求。为了实现这一点，我创建了许多线程（数量大约 50 个）。每分钟的请求总数可能会增加到 10000。 Windows服务形式的应用程序运行良好几分钟，然后遇到操作超时错误。

我尝试过常见的怀疑，例如增加默认连接限制，关闭网络响应对象。由于请求在服务器上花费的时间并不多，因此我还设置了请求Timeout and 读写超时至 5 秒。 下面是不同线程重复调用的代码片段。

// Below line is executed at the start of application
ServicePointManager.DefaultConnectionLimit = 15000;

// Below code is executed at repeatedly by different threads
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
request.Host = hostName;
request.Proxy = null;
request.UserAgent = "Windows Service";
byte[] bytes = new byte[0];
if (body != null)
{
    bytes = System.Text.Encoding.ASCII.GetBytes(body);
    request.ContentType = "text/xml; encoding='utf-8'";
    request.ContentLength = bytes.Length;
}
request.Method = "POST";
request.Timeout = 5000;
request.ReadWriteTimeout = 5000;

request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(username + ":" + password));

request.CookieContainer = this.cookieContainer;

if (body != null)
{
    Stream requestStream = request.GetRequestStream();
    requestStream.Write(bytes, 0, bytes.Length);
    requestStream.Close();
}

HttpWebResponse httpResponse = (HttpWebResponse)request.GetResponse();

using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
     responseText = streamReader.ReadToEnd();
}
httpResponse.Close();

ServicePointManager.DefaultConnectionLimit限制向给定服务器发出的 Web 请求的数量。一般默认是2 or 10.

如果您要对该 Web 服务进行 50 个并行调用，则应该设置ServicePointManager.DefaultConnectionLimit（在应用程序启动时）到更大的数字（例如40-50).

此外，您没有调用Close or Dispose on request。你应该这样做，或者让using为您照顾。