Server 2008 上 HTTPWebRequest 的性能问题（在 xp 上很好）答案

【问题标题】：Performance Issue With HTTPWebRequest on Server 2008 (fine on xp)Server 2008 上 HTTPWebRequest 的性能问题（在 xp 上很好）
【发布时间】：2011-03-04 13:09:36
【问题描述】：

我开发了一个 .net 3.5 应用程序，它使用 HTTPWebRequest 从供应商 Web 服务器获取数据，然后返回一个 XML 文档。在我自己的 xp（32 位）工作站上，它运行得非常快。

在服务器上它要慢得多。供应商的 16k 响应最多需要 20-30 秒，而在我的 PC 上则需要 1 秒。

服务器是在 ESX 上以 64 位模式运行 windows server 2008 的虚拟机。我在服务器上安装了 Internet Explorer，并在 IE 中发出相同的请求，与我的应用程序相反，页面的加载时间与我的工作站上的时间相似。

代码如下：

private static XElement FetchXml(string uri)
{
    int retryInterval = 500;

    for (int retry = 1; retry < RETRY_MAX; ++retry)
    {
        Stopwatch stopWatch = Stopwatch.StartNew();

        try
        {
            var request = HttpWebRequest.Create(uri);

            request.Proxy = new WebProxy("<the corporate proxy>", 8080);

            // 3 minute timeout on individual web requests
            request.Timeout = 1000 * 60 * 3;

            using (var response = request.GetResponse())
            {
                using (var stream = response.GetResponseStream())
                {
                    using (var reader = new StreamReader(stream))
                    {
                        XElement xml = XElement.Load(reader);
                        //log.InfoFormat("Fetched (Uri={0}, Size={1} bytes, Elapsed={2:N2}s).", uri, xml.ToString().Length, stopWatch.Elapsed.TotalSeconds);
                        return xml;
                    }
                }
            }
        }
        catch (Exception ex)
        {
            //log.ErrorFormat("Error fetching Xml (Uri={0}) : {1}", uri, ex.Message);
        }
        //log.InfoFormat("Retrying fetch after interval (Attempt#={0}, Interval={1}s)",
        //  retry, (double)retryInterval/1000);

        System.Threading.Thread.Sleep(retryInterval);

        // Back off for next retry if it occurs.
        retryInterval *= 2;
    }

    string msg = String.Format("Error fetching Xml - exhausted maximum retries (Uri={0}, MaxRetries={1}).",
        uri,
        RETRY_MAX);     

    throw new ApplicationException(msg);
}

在昨天研究该问题后，我已经测试了以下所有内容：

ServicePointManager.CheckCertificateRevocationList = false;
ServicePointManager.DefaultConnectionLimit = 65000;
ServicePointManager.Expect100Continue = false;

这些都没有帮助。我还看到它表明代理可能会导致这些问题并且可以被绕过，不幸的是不在这个环境中，而且我认为这可能是代理错误，因为我在我的工作站上使用了相同的代理。

我还捕获了一些 Microsoft 网络监视器跟踪，有趣的是，服务器上从远程站点到我的应用程序的数据包大小要小得多。在我的工作站上它们大约是 1400 字节，而在服务器上它们更像是 300 字节，虽然我对 TCP 不太熟悉，但似乎有很多喋喋不休的话题让 http 延续来构建完整的消息。因此，在我的工作站上，总有效负载大约有 4 条入站消息，其中 3 条出站，而在服务器上，它是 19 条入站消息，出站数量相似。这可能解释了性能问题，但我不明白为什么会这样。当我在服务器上的 IE 中加载页面时，它的请求数量很少，数据包大小很大。

我的 XP 工作站上的网络监视器：

HTTP:Request, GET http://xml.vendor.com/datapage/, Query:version=6.0
HTTP:Response, HTTP/1.1, Status: Ok, URL: http://xml.vendor.com/datapage/
HTTP:HTTP Payload, URL: http://xml.vendor.com/datapage/
 TCP:Flags=...A...., SrcPort=2192, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3206279401, Ack=33242842, Win=64512 (scale factor 0x0) = 64512
 TCP:[Continuation to #915]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=2192, PayloadLen=1360, Seq=33242842 - 33244202, Ack=3206279401, Win=65535 (scale factor 0x0) = 65535
 TCP:[Continuation to #915]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=2192, PayloadLen=1360, Seq=33244202 - 33245562, Ack=3206279401, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=2192, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3206279401, Ack=33245562, Win=64512 (scale factor 0x0) = 64512
 TCP:[Continuation to #915]Flags=...AP..., SrcPort=HTTP Alternate(8080), DstPort=2192, PayloadLen=557, Seq=33245562 - 33246119, Ack=3206279401, Win=65535 (scale factor 0x0) = 65535 
 TCP:Flags=...A...., SrcPort=2192, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3206279401, Ack=33246119, Win=63955 (scale factor 0x0) = 63955

同样的代码+请求在服务器上运行：

HTTP:Request, GET http://xml.vendor.com/datapage/, Query:version=6.0
HTTP:Response, HTTP/1.1, Status: Ok, URL: http://xml.vendor.com/datapage/
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24013122, Win=255 (scale factor 0x8) = 65280
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=255, Seq=24013122 - 24013377, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24013377, Win=254 (scale factor 0x8) = 65024
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=254, Seq=24013377 - 24013631, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24013631, Win=253 (scale factor 0x8) = 64768
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=253, Seq=24013631 - 24013884, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24013884, Win=252 (scale factor 0x8) = 64512
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=252, Seq=24013884 - 24014136, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24014136, Win=251 (scale factor 0x8) = 64256
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=251, Seq=24014136 - 24014387, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24014387, Win=256 (scale factor 0x8) = 65536
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=256, Seq=24014387 - 24014643, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24014643, Win=255 (scale factor 0x8) = 65280
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=255, Seq=24014643 - 24014898, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24014898, Win=254 (scale factor 0x8) = 65024
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=254, Seq=24014898 - 24015152, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24015152, Win=253 (scale factor 0x8) = 64768
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=253, Seq=24015152 - 24015405, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24015405, Win=252 (scale factor 0x8) = 64512 
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=252, Seq=24015405 - 24015657, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24015657, Win=251 (scale factor 0x8) = 64256
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=251, Seq=24015657 - 24015908, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24015908, Win=256 (scale factor 0x8) = 65536
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=256, Seq=24015908 - 24016164, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24016164, Win=255 (scale factor 0x8) = 65280
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=255, Seq=24016164 - 24016419, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24016419, Win=254 (scale factor 0x8) = 65024
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=254, Seq=24016419 - 24016673, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24016673, Win=253 (scale factor 0x8) = 64768
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=253, Seq=24016673 - 24016926, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24016926, Win=252 (scale factor 0x8) = 64512
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=252, Seq=24016926 - 24017178, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24017178, Win=251 (scale factor 0x8) = 64256
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=251, Seq=24017178 - 24017429, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24017429, Win=256 (scale factor 0x8) = 65536
 TCP:[Continuation to #192]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=256, Seq=24017429 - 24017685, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24017685, Win=255 (scale factor 0x8) = 65280
 TCP:[Continuation to #192]Flags=...AP..., SrcPort=HTTP Alternate(8080), DstPort=58401, PayloadLen=181, Seq=24017685 - 24017866, Ack=3779234716, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=58401, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=3779234716, Ack=24017866, Win=254 (scale factor 0x8) = 65024

服务器上的 IE 正在获取相同的页面：

HTTP:Request, GET http://xml.vendor.com/datapage/, Query:version=6.0
 TCP:Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=53132, PayloadLen=0, Seq=20851875, Ack=2273238303, Win=65535 (scale factor 0x0) = 65535
HTTP:Response, HTTP/1.1, Status: Ok, URL: http://xml.vendor.com/datapage/
HTTP:HTTP Payload, URL: http://xml.vendor.com/datapage/
 TCP:[Continuation to #345]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=53132, PayloadLen=1360, Seq=20853598 - 20854958, Ack=2273238303, Win=65535 (scale factor 0x0) = 65535
 TCP:[Continuation to #345]Flags=...A...., SrcPort=HTTP Alternate(8080), DstPort=53132, PayloadLen=1360, Seq=20854958 - 20856318, Ack=2273238303, Win=65535 (scale factor 0x0) = 65535
 TCP:[Continuation to #345]Flags=...AP..., SrcPort=HTTP Alternate(8080), DstPort=53132, PayloadLen=557, Seq=20856318 - 20856875, Ack=2273238303, Win=65535 (scale factor 0x0) = 65535
 TCP:Flags=...A...., SrcPort=53132, DstPort=HTTP Alternate(8080), PayloadLen=0, Seq=2273238303, Ack=20856875, Win=16425 (scale factor 0x2) = 65700

有趣的一点是，在缓慢的请求中，跟踪永远不会捕获“HTTP Payload”。那里有什么奇怪的事情吗？一旦请求最终在服务器上完成，尽管如此，数据仍然是正确的。

【问题讨论】：

+1 表示经过充分研究和正确提出的问题。抱歉，我无法提供更多帮助。

标签： performance sql-server-2008 64-bit httpwebrequest frame

【解决方案1】：

这个答案看起来可能是相关的......也许.net在阅读您可能设置为让IE正常工作的默认代理设置时窒息：HTTPWebResponse + StreamReader Very Slow p>

当您在代码中设置代理时，您可以跳过检测。

【讨论】：

嗨 - 感谢您的建议。我刚刚测试了这个并且没有骰子 - 我认为当我手动设置代理时，它无论如何都不会尝试获取默认代理。从我的日志中也可以看出，初始响应有点慢，但从那时起数据的加载也非常慢。所以这将是在代理谈判等之后。
看看从XP盒子到目的地，然后是服务器和目的地的路线（运行tracert）有什么区别。这将揭示您的数据经过的不同之处。

【解决方案2】：

查看您的捕获，您的客户端代码 TCP 堆栈似乎正在向服务器广播一个 255 字节的 TCP 窗口。这就是目标代理服务器最多只发回 255 个字节的原因。

这是您在其中运行代码的控制台应用程序吗？是否有其他代码正在改变 TCP 窗口大小？

【讨论】：

【解决方案3】：

这已通过禁用似乎表现异常的 windows tcp 自动调整来解决！

谢谢，

丹

【讨论】：