HttpClient 在指定超时之前超时 [英] HttpClient timeouts before the timeout specified

问题描述

我正在使用 WP8 的 HttpClient 并执行 Post 请求.我知道通话可能需要很长时间，因为我实际上是在模拟慢速网络场景.因此，我将 HttpClient.Timeout 相应地设置为 5 分钟.

I'm using HttpClient from WP8 and do a Post request. I know the call may take long time as I'm actually simulating slow network scenarios. Therefore I set the HttpClient.Timeout accordingly to 5 minutes.

但是，我在 60 秒左右收到超时.我相信超时不起作用.我相信 WP 存在这个问题，如本问题所述:HttpClient Portable 返回 404 notfound on WP8.

However, I get a Timeout at around 60s. I believe the Timeout is not working. I believe there is an issue with this for WP as stated in this question: HttpClient Portable returns 404 notfound on WP8.

他们使用了一种解决方法，但这不适用于我的场景.其实我很想等很久.

They use a workaround but that does not applies to my scenario. I do actually want to wait for long time.

我的问题:

1) 这是 WP8 的 HttpClient 的错误/问题还是我没有正确设置?2)您是否想到仍然使用HttpClient的解决方法?

1) Is it a bug/issue of HttpClient for WP8 or I'm not setting it properly? 2) Do you think of a workaround still using HttpClient?

我读过可能 HttpWebRequest 是一个选项.但是，我相信 HttpClient 应该是这种简单"场景的理想选择.

I've read that maybe HttpWebRequest is an option. However, I believe HttpClient should be ideal for this 'simple' scenario.

我的代码很简单:

private static async Task<HttpResponseMessage> PostAsync(Uri serverUri, HttpContent httpContent)
{
    var client = new HttpClient();
    client.Timeout = TimeSpan.FromMinutes(5);
    return await client.PostAsync(serverUri, httpContent).ConfigureAwait(false);
}

服务器收到请求并在处理它时，客户端中止.

The server receives the request and while is processing it, the client aborts.

更新:HttpClient.PostAsyn 返回的 HttpResponseMessage 是这个 "{StatusCode: 404, ReasonPhrase: '', Version: 0.0, Content: System.Net.Http.StreamContent，标题:{ 内容长度:0 }}".正如我所说，服务器已找到并正在接收数据并对其进行处理.

UPDATE: The HttpResponseMessage returned by HttpClient.PostAsyn is this "{StatusCode: 404, ReasonPhrase: '', Version: 0.0, Content: System.Net.Http.StreamContent, Headers: { Content-Length: 0 }}". As I said, the server is found and is receiving the data and processing it.

推荐答案

经过一些搜索和一些测试，我得出的结论是，问题出在 Windows Phone 本身，并且它有 60 秒的超时时间(与 HttpClient 无关))，据我所知，这不能改变.请参阅 http://social.msdn.microsoft.com/Forums/en-US/faf00a04-8a2e-4a64-b1c1-74c52cf685d3/httpwebrequest-60-seconds-timeout.

After some search and some tests I've came to the conclusion that the problem is Windows Phone itself and that it has a 60 seconds timeout (irrespective of the HttpClient) and that cannot be changed to my knowledge. See http://social.msdn.microsoft.com/Forums/en-US/faf00a04-8a2e-4a64-b1c1-74c52cf685d3/httpwebrequest-60-seconds-timeout.

因为我也在对服务器进行编程，所以我将尝试上面提供的链接中 Darin Rousseau 的建议，特别是发送一个 OK 然后做一些更多的处理.

As I'm programming the server as well, I will try the advice by Darin Rousseau in the link provided above, specifically to send an OK and then do some more processing.

更新:问题似乎是此处所述的 Windows Phone 模拟器:http://social.msdn.microsoft.com/forums/wpapps/en-us/6c114ae9-4dc1-4e1f-afb2-a6b9004bf0c6/httpclient-doesnt-work-on-windows-phone?forum=wpdevelop.根据我的经验，如果 60 秒内没有听到任何消息，tcp 连接就会超时.

UPDATE: The problem seems to be the Windows Phone emulator as stated here: http://social.msdn.microsoft.com/forums/wpapps/en-us/6c114ae9-4dc1-4e1f-afb2-a6b9004bf0c6/httpclient-doesnt-work-on-windows-phone?forum=wpdevelop. In my experience the tcp connection times-out if it doesn't hear anything for 60s.

因此我的解决方案是使用 Http 标头字符作为保持活动的方式.第一行 Http 头响应总是以 HTTP/1.0 开头.所以我一个一个发送字符，它们之间的延迟 <60 秒.当然，如果响应准备好，剩下的所有内容都会立即发送.这会花费一些时间，例如，如果使用每 9 个字符 50 秒的延迟，我们会得到大约 450 秒.

Therefore my solution is to use the Http header characters as a way of keep alive. The first line Http header response always starts with HTTP/1.0. So I send the characters one by one with a delay <60s between them. Of course, if the response gets ready, everything that is left is sent right away. This buys some time, for instance if using a delay of 50s per 9 character we get about 450s.

这是我的学位项目，所以我不建议将其用于生产.

This is a project for my degree so I wouldn't recommend it for production.

顺便说一句，我还尝试使用其他字符代替标头的子字符串，例如空格字符，但这会导致违反 http 协议.

By the way, I also tried with other characters instead the sub string of the header, for instance space character, but that results in a http protocol violation.

这是代码的主要部分:

    private const string Header1 = @"HTTP/1.0 ";
    private int _keepAliveCounter = 0;
    private readonly object _sendingLock = new object();
    private bool _keepAliveDone = true;

    private void StartKeepAlive()
    {
        Task.Run(() => KeepAlive());
    }

    /// <summary>
    /// Keeps the connection alive sending the first characters of the http response with an interval.
    /// This is a hack for Windows Phone 8 that need reponses within 60s interval.
    /// </summary>
    private void KeepAlive()
    {
        try
        {
            _keepAliveDone = false;
            _keepAliveCounter = 0;
            while (!_keepAliveDone && _keepAliveCounter < Header1.Length)
            {
                Task.Delay(TimeSpan.FromSeconds(50)).Wait();
                lock (_sendingLock)
                {
                    if (!_keepAliveDone)
                    {
                        var sw = new StreamWriter(OutputStream);
                        sw.Write(Header1[_keepAliveCounter]);
                        Console.Out.WriteLine("Wrote keep alive char '{0}'", Header1[_keepAliveCounter]);
                        _keepAliveCounter++;
                        sw.Flush();
                    }
                }
            }
            _keepAliveCounter = 0;
             _keepAliveDone = true;
        }
        catch (Exception e)
        {
            // log the exception
            Console.Out.WriteLine("Error while sending keepalive: " + e.Message);
        }
    }

然后，实际处理发生在不同的线程中.

Then, the actual processing happens in a different thread.

感谢评论和批评.

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