C# GetResponse не возвращается

Question

У меня странная проблема. Мой .NET DataController отправляет ответ на сервер Java (REST). Все работает нормально, но когда я отправляю ответ очень часто, вдруг метод GetResponse не возвращается, просто зависает. Я не знаю, в чем проблема.

Вот мой код

ServicePointManager.DefaultConnectionLimit = 20; 

public string HttpGet(string url, string requestAccept) 
{ 
    if(string.IsNullOrEmpty(url)) 
    throw new Exception("HttpGet: no REST service URL provided"); 
    if(string.IsNullOrEmpty(requestAccept)) 
    requestAccept = defaultRequestAccept; 

    if(!url.Equals("pc/alive")) 
    { 
    if(string.IsNullOrEmpty(SessionId)) 
    { 
     if(string.IsNullOrEmpty(Authorization())) 
     throw new WebException("HttpGet: no login"); 
    } 
    } 

    int tries = RestAccessData.MaxReconnect; 
    string result = string.Empty; 

    do 
    { 
    try 
    { 
     var request = NewWebRequest(url, "GET", false, true, requestAccept); 

     using(var response = request.GetResponse() as HttpWebResponse) 
     { 
     UpdateSessionId(response); 

     HttpStatusCode statusCode = response.StatusCode; 
     LOG.Debug("...StatusCode: {0} ({1})", (int) response.StatusCode, response.StatusDescription); 

     if((int) response.StatusCode < 500) 
      lastContactWithServer = DateTime.Now.Ticks; 

     switch(statusCode) 
     { 
     // Informational 1xx 
     case HttpStatusCode.Continue: // 100 
     case HttpStatusCode.SwitchingProtocols: // 101 

      throw new HttpResponseException(response); 

     // Successful 2xx 
     case HttpStatusCode.OK: // 200 

      result = ReadContent(response); 
      response.Close(); 

      return (result); 

     case HttpStatusCode.NoContent: // 204 The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation. 

      response.Close(); 
      return (string.Empty); 

     case HttpStatusCode.Created: // 201 
     case HttpStatusCode.NonAuthoritativeInformation: // 203 

      result = ReadContent(response); 
      throw new HttpResponseException(response, result); 

     case HttpStatusCode.Accepted: // 202 The request has been accepted for processing, but the processing has not been completed. 
     case HttpStatusCode.ResetContent: // 205 The server has fulfilled the request and the user agent SHOULD reset the document view which caused the request to be sent. 
     case HttpStatusCode.PartialContent: // 206 The server has fulfilled the partial GET request for the resource. 

      throw new HttpResponseException(response); 

     case HttpStatusCode.Unauthorized: 

      throw new HttpResponseException(response); 

     default: 

      throw new HttpResponseException(response); 
     } 
     } 
    } 
    catch(WebException ex) 
    { 
     HandleWebException(ex); 
    } 
    catch(HttpResponseException ex) 
    { 
     throw ex; 
    } 
    catch(SystemException ex) 
    { 
     LOG.Error(ex, "caused a(n) {0}", ex.GetType().Name); 
    } 
    catch(Exception ex) 
    { 
     LOG.Warn(ex, "HttpGet: An error occured while trying to contact the server. Reason: {0}", ex.Message); 
     throw new UserException("An error occured while trying to contact the server.", ex); 
    } 
    } 
    while(0 < tries--); 

    return (string.Empty); 
} 

private HttpWebRequest NewWebRequest(string urlAsString, string requestType, bool withContentType, bool applicationJson, string requestAccept) 
{ 
    urlAsString = string.Format("{0}{1}", RestAccessData.GetUrl(), EncodeUrl(urlAsString)); 
    Uri url; 

    if(!Uri.TryCreate(urlAsString, UriKind.Absolute, out url)) 
    throw new NotSupportedException("url is not compatible"); 

    LOG.Info("RESTUrl {0}", urlAsString); 

    try 
    { 
    var request = HttpWebRequest.Create(url) as HttpWebRequest; 

    if(!string.IsNullOrEmpty(SessionId)) 
    { 
     CookieContainer cookies = new CookieContainer(); 
     Cookie cookie = new Cookie 
     { 
     Name = "JSESSIONID", 
     Value = SessionId, 
     Domain = url.Host 
     }; 

     cookies.Add(cookie); 
     request.CookieContainer = cookies; 
    } 

    request.Timeout = RestAccessData.Timeout; 
    request.Method = requestType; 
    request.AllowAutoRedirect = true; 
    request.AllowWriteStreamBuffering = true; 
    request.KeepAlive = false; 
    request.ContentLength = 0; 
    request.Headers["Accept-Charset"] = "utf-8"; 
    request.Accept = requestAccept; 
    request.UserAgent = LvsClient; 

    if(withContentType) 
     request.ContentType = applicationJson ? defaultApplicationJson : defaultApplicationWwwForm; 

    if(!string.IsNullOrEmpty(credential.UserName) && !string.IsNullOrEmpty(credential.Password)) 
     request.Headers["Authorization"] = string.Format("Basic {0}", Convert.ToBase64String(Encoding.UTF8.GetBytes(string.Format("{0}:{1}", credential.UserName, credential.Password)))); 

    return (request); 
    } 
    catch(Exception ex) 
    { 
    throw new UserException(TH.Translate("NewWebRequest caused an error"), ex); 
    } 
} 

Любые идеи, где проблема?

Answer 1

Я нашел решение. Очень полезной является статья MSDN о Understanding MaxServicePointIdleTime and DefaultConnectionLimit. После того, как я играю с MaxServicePointIdleTime собственности и прочитать комментарий

change the connection limit at any time

Я нашел хороший баланс между соединительным живым и закрытием соединения. Мой клиент отлично работает после игры с MaxServicePointIdleTime и DefaultConnectionLimit.

Answer 2

Эта линия делает меня неудобным:

using(var response = request.GetResponse() as HttpWebResponse) 

Если ответ не HttpWebResponse, то он никогда не будет утилизировать - оператор as даст вам `нуль.