c# - WebClient的UploadFile大小限制

Question

这个问题已经有答案了:

Is there an upload limit when using Web Client in C#? (2 个回答)

已关闭 7 年前。

我在将 zip 文件上传到 Azure 进行 Web 作业时遇到了问题。

当 zip 文件大小小于 10MB 时，一切顺利，但是当尝试上传更大的文件时，我收到此异常:

The stream does not support concurrent IO read or write operations

堆栈:

• at System.Net.ConnectStream.InternalWrite(Boolean async, Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
• at System.Net.ConnectStream.Write(Byte[] buffer, Int32 offset, Int32 size)
• at System.Net.WebClient.UploadBitsState.WriteBytes()
• at System.Net.WebClient.UploadBits(WebRequest request, Stream readStream, Byte[] buffer, Int32 chunkSize, Byte[] header, Byte[] footer, CompletionDelegate uploadCompletionDelegate, CompletionDelegate downloadCompletionDelegate, AsyncOperation asyncOp)
• at System.Net.WebClient.UploadFile(Uri address, String method, String fileName)

这是我的代码:

var client = new MyWebClient
{
    Credentials = new NetworkCredential(webSite.UserName, webSite.Password),                
};
client.Headers.Add(HttpRequestHeader.ContentType, "application/zip");
client.Headers.Add("Content-Disposition", $"attachment; filename={appFile}");

var response = client.UploadFile(uploadUri, "PUT", filePath);

哪里MyWebClient是 WebClient 的实现我需要在其中设置超时:

private class MyWebClient : WebClient
{
    protected override WebRequest GetWebRequest(Uri uri)
    {
        WebRequest w = base.GetWebRequest(uri);
        w.Timeout = 20 * 60 * 1000;
        return w;
    }
}

知道尺寸限制在哪里吗？我确信它是客户端而不依赖于 .Net Framework，因为我对其中的几个进行了测试。

编辑解决方案是通过将 WebClient 强制转换为 HttpWebRequest 来强制 AllowWriteStreamBuffering 为 false:

            protected override WebRequest GetWebRequest(Uri uri)
            {
                WebRequest w = base.GetWebRequest(uri);
                w.Timeout = 20 * 60 * 1000;
                var httpRequest = w as HttpWebRequest;
                if (httpRequest != null)
                {
                    httpRequest.AllowWriteStreamBuffering = false;
                }
                return w;
            }

Answer 1

此行为记录在此博客条目 http://vikeed.blogspot.co.uk/2011/03/uploading-large-files-using-http-put-in.html 中建议添加以下内容；

 HttpWebRequest request = new ... 
 request.AllowWriteStreamBuffering = false;

此处发布了相同的问题 C# HttpClient PUT这表明使用 AllowAutoRedirect = false 会导致此错误。

您可以尝试按照这两篇类似帖子中的建议修改您的设置，看看是否可以纠正您的错误。