OutOfMemoryException when send big file 500MB using FileStream ASPNET

Question

I\'m using Filestream for read big file (> 500 MB) and I get the OutOfMemoryException.

I use Asp.net , .net 3.5, win2003, iis 6.0

I want this in my app:

Answer 1

I came across this question in my search to return a FileStreamResult from a controller, as I kept running into issues while working with large streams due to .Net trying to build the entire response all at once. Pavel Morshenyuk's answer was a huge help, but I figured I'd share the BufferedFileStreamResult that I ended up with.

/// 
Based upon https://stackoverflow.com/a/3363015/595473 
public class BufferedFileStreamResult : System.Web.Mvc.FileStreamResult
{
    public BufferedFileStreamResult(System.IO.Stream stream, string contentType, string fileDownloadName)
        : base(stream, contentType)
    {
        FileDownloadName = fileDownloadName;
    }

    public int BufferSize { get; set; } = 16 * 1024 * 1024;//--16MiB

    protected override void WriteFile(System.Web.HttpResponseBase response)
    {
        try
        {
            response.Clear();
            response.Headers.Set("Content-Disposition", $"attachment; filename={FileDownloadName}");
            response.Headers.Set("Content-Length", FileStream.Length.ToString());

            byte[] buffer;
            int bytesRead;

            while (response.IsClientConnected)//--Prevent infinite loop if user disconnects
            {
                buffer = new byte[BufferSize];

                //--Read the data in buffer
                if ((bytesRead = FileStream.Read(buffer, 0, BufferSize)) == 0)
                {
                    break;//--Stop writing if there's nothing left to write
                }

                //--Write the data to the current output stream
                response.OutputStream.Write(buffer, 0, bytesRead);

                //--Flush the data to the output
                response.Flush();
            }
        }
        finally
        {
            FileStream?.Close();
            response.Close();
        }
    }
}

Now, in my controller, I can just

return new BufferedFileStreamResult(stream, contentType, fileDownloadName);