c# - 30ish スレッド後に HttpWebRequest がタイムアウトし始める

Question

スレッドを開始するために次のコードを実行しています。

        stpStartInfo.MaxWorkerThreads = Convert.ToInt32(parserThreadCount.Value);
        stpStartInfo.MinWorkerThreads = 1;
        _smartThreadPool2 = new Smart.SmartThreadPool(stpStartInfo);

        string f = sourceFileName.Text;
        int totCount = countLinesInFile(f);

        using (StreamReader r = new StreamReader(f))
        {
            int iia = 0;
            string line;
            while ((line = r.ReadLine()) != null)
            {
                if (!string.IsNullOrEmpty(line)) 
                {
                    _smartThreadPool2.QueueWorkItem(
                    new Amib.Threading.Func<string, int, int, int>(checkSource),
                    line, iia, totCount);

                    iia++;
                }
            }
        }

私のスレッドは、この HttpWebRequest を実行しています:

        try
        {
            HttpWebRequest _wReq;
            HttpWebResponse _wResp;
            System.IO.StreamReader _sr;
            System.Text.ASCIIEncoding _enc = new System.Text.ASCIIEncoding();
            _wReq = (HttpWebRequest)WebRequest.Create(PAGE_URL);
            _wReq.CookieContainer = cookieCont;
            _wReq.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
            _wReq.ReadWriteTimeout = 10000;
            _wReq.Timeout = 10000;
            _wReq.ProtocolVersion = HttpVersion.Version10;
            _wReq.KeepAlive = false;





            _wResp = (HttpWebResponse)_wReq.GetResponse();
            _sr = new System.IO.StreamReader(_wResp.GetResponseStream());
            html = _sr.ReadToEnd();


            _sr.Close();
            _cookies = _wReq.CookieContainer;
            _wResp.Close();
        }
        catch (WebException ex)
        {

            if (ex.Status == WebExceptionStatus.ProtocolError && ex.Response != null)
            {
                var resp = (HttpWebResponse)ex.Response;
                if (resp.StatusCode == HttpStatusCode.ServiceUnavailable)
                {

                }

            }
        }

それは完全に機能しますが、30ish スレッドの後、要求がタイムアウトし始めます..

これを回避する方法はありますか？:)