HttpClient 收到服务器响应后无法停止流式传输

Question

我一直在为 .NET 4.5 中的 HttpClient 苦苦挣扎。通过分块传输将大量流式上传到 WebApi 端点，当服务器已经以不成功状态代码（未找到、身份验证、授权、验证错误等）响应中间请求时，它无法停止。

查看ConnectStream 类中的调试器，它知道它从服务器收到了不成功的状态。从服务器接收到的 HTTP 状态和数据将被存储以备后用，从那一刻起，它只是假装从流中读取直到结束。从那一刻起，网络上没有任何内容，稍后通过HttpResponseMessage 提供响应。这种无法解释的行为给我带来了巨大的问题，因为有问题的流可能非常大。无用的时间花在阅读流直到最后，加上不正确的上传报告被显示给用户。我停止了 Web 服务器、远程机器，甚至禁用了本地网络接口。 HttpClient 不在乎。它继续从提供的流中读取。

我尝试使用 HttpCompletionOption.ResponseHeadersRead 和 StreamedContent 或 PushStreamContent。相同的行为。我也尝试过使用HttpWebRequest，但是这不允许在输出流上写入和同时读取传入流。有没有办法阻止客户端在收到服务器的响应后发送或假装发送流？为什么HttpClient 会这样？

var httpClientHandler = new WebRequestHandler
    {
         AllowAutoRedirect = true,
         PreAuthenticate = false,
         CookieContainer = cookieContainer,
         UseCookies = true,
         CachePolicy = new RequestCachePolicy(RequestCacheLevel.NoCacheNoStore),                                        
         AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip
    };
var httpClient = new HttpClient(_httpClientHandler)
    {
          BaseAddress = baseApiUrl,                                  
          Timeout = Timeout.InfiniteTimeSpan; 
    };
httpClient.DefaultRequestHeaders.TransferEncodingChunked = true;
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/plain", 0.8));
httpClient.DefaultRequestHeaders.AcceptCharset.Add(new StringWithQualityHeaderValue("UTF-8"));
httpClient.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue(appName, appVersion));

var requestContent = new StringContent(serializedRequest, Encoding.UTF8, "application/json");

// the monitored stream is an implementation of the stream that proxies the calls to a classic file stream
// here I monitor the calls made to Read(byte[] buffer, int offset, int count) method 
// tried with both CanSeek = false or true - the HttpClient reads the whole stream no matter what.
var streamedContent =  new StreamContent(monitoredStream);
streamedContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
    {
        FileName = "upload.bin",
        Size = monitoredStream.Length       
    };

var httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, relativeUrl)
    {
        Content = new MultipartFormDataContent
            {
                requestContent,
                streamedContent    
            }
    };

// the Owin middleware could fail checking authentication, an authorization error could occur, 
//    or the WebApi controller could receive the first part of the multipart data and reject the request
// from the moment data was received from the server, mid-stream, I could safely unplug the network cable 
// socket erros are being ignored, actually the underlying socket is no longer used
// the response message contains the status code and data received during the transmission of the request at the end of this call
var httpResponseMessage = await _httpClient.SendAsync(httpRequestMessage, HttpCompletionOption.ResponseHeadersRead, cancellationToken);

Answer 1

这是HttpClient 中已确认的限制。 Here is the Microsoft Connect case。也许它会在下一个版本中实现，但它不会影响投票。