将文件上载到服务器会引发内存不足异常

Question

我正在尝试使用asp.net web api实现文件上传系统,我遇到了问题.我试图将多部分表单数据放入内存流中,以便根据服务层实现将其写入磁盘或blob存储.问题是它适用于小文件,但我试图上传一个291 MB的文件,它正在抛出一个内存不足的例外.这是代码:

if (!Request.Content.IsMimeMultipartContent())
{
    Request.CreateErrorResponse(HttpStatusCode.UnsupportedMediaType, "Request must be multipart.");
}

var provider = new MultipartMemoryStreamProvider();

try
{
    await Request.Content.ReadAsMultipartAsync(provider);

    var infoPart = provider.Contents.Where(x => x.Headers.ContentDisposition.Name.Replace("\"", string.Empty) == "fileInfo").SingleOrDefault();
    var filePart = provider.Contents.Where(x => x.Headers.ContentDisposition.Name.Replace("\"", string.Empty) == "filePart" && x.Headers.ContentDisposition.FileName != null).Single();
    byte[] file = null;

    using (Stream stream = filePart.ReadAsStreamAsync().Result)
    {
        using (MemoryStream memory = new MemoryStream())
        {
            stream.CopyTo(memory);
            file = memory.ToArray();
        }
    }

    string fileContentType = filePart.Headers.ContentType.MediaType;

    FileDto result = _fileService.AddFileToResource(Variables);
    string uri = Url.Link("DefaultGet", new { id = result.ID });
    return Request.CreateResponse(HttpStatusCode.OK);

抛出错误的部分是在

await Request.Content.ReadAsMultipartAsync(provider);

确切的错误是

将MIME多部分正文部分写入输出流时出错.

内在的例外

抛出了类型'System.OutOfMemoryException'的异常.

我曾尝试创建一个自定义BufferPolicySelector所示的第二个答案这个职位和其他许多地方,但似乎并没有帮助的.

我还添加到了我的web.config:

<httpRuntime targetFramework="4.5" maxRequestLength="307200"/>

和

<security>
  <requestFiltering>
    <requestLimits maxAllowedContentLength="367001600"/>
  </requestFiltering>
</security>

Answer 1

一种解决方案是使用MultipartFormDataStreamProvider而不是MultipartMemoryStreamProvider在调用期间避免内存不足异常

Request.Content.ReadAsMultipartAsync(..)

在尝试使用MemoryStreamProvider同时读取大文件(> 100 MB)的MultiPart文件内容时,我遇到了类似的问题.对我有用的工作是使用MultipartFormDataStreamProvider.在ReadAsMultipartAsync调用期间将文件写入磁盘,如果在内存中需要,可以稍后重新加载.

以下是一个例子:

在Web API中发送HTML表单数据:文件上载和多部分MIME

    string root = HttpContext.Current.Server.MapPath("~/App_Data");
    var provider = new MultipartFormDataStreamProvider(root);

    try
    {
        // Read the form data.
        await Request.Content.ReadAsMultipartAsync(provider);

        // This illustrates how to get the file names.
        foreach (MultipartFileData file in provider.FileData)
        {
            Trace.WriteLine(file.Headers.ContentDisposition.FileName);
            Trace.WriteLine("Server file path: " + file.LocalFileName);
        }
        return Request.CreateResponse(HttpStatusCode.OK);
    }
    catch(...)