C# Download big file from Server with less memory consumption

Question

I have a big file of memory size 42 mb. I want to download the file with less memory consumption.
Controller Code

public ActionResult Download()
{
    var filePath = "file path in server";
    FileInfo file = new FileInfo(filePath);
    Response.ContentType = "application/zip";                        
    Response.AppendHeader("Content-Disposition", "attachment; filename=folder.zip");                   
    Response.TransmitFile(file.FullName);
    Response.End(); 
}

alernative method tried with Stream

public ActionResult Download()
{           
    string failure = string.Empty;
    Stream stream = null;
    int bytesToRead = 10000;


    long LengthToRead;
    try
    {
        var path = "file path from server";
        FileWebRequest fileRequest = (FileWebRequest)FileWebRequest.Create(path);
        FileWebResponse fileResponse = (FileWebResponse)fileRequest.GetResponse();

        if (fileRequest.ContentLength > 0)
            fileResponse.ContentLength = fileRequest.ContentLength;

        //Get the Stream returned from the response
        stream = fileResponse.GetResponseStream();

        LengthToRead = stream.Length;

        //Indicate the type of data being sent
        Response.ContentType = "application/octet-stream";

        //Name the file 
        Response.AddHeader("Content-Disposition", "attachment; filename=SolutionWizardDesktopClient.zip");
        Response.AddHeader("Content-Length", fileResponse.ContentLength.ToString());

        int length;
        do
        {
            // Verify that the client is connected.
            if (Response.IsClientConnected)
            {
                byte[] buffer = new Byte[bytesToRead];

                // Read data into the buffer.
                length = stream.Read(buffer, 0, bytesToRead);

                // and write it out to the response's output stream
                Response.OutputStream.Write(buffer, 0, length);

                // Flush the data
                Response.Flush();

                //Clear the buffer
                LengthToRead = LengthToRead - length;
            }
            else
            {
                // cancel the download if client has disconnected
                LengthToRead = -1;
            }
        } while (LengthToRead > 0); //Repeat until no data is read

    }
    finally
    {
        if (stream != null)
        {
            //Close the input stream                   
            stream.Close();
        }
        Response.End();
        Response.Close();
    }
    return View("Failed");
}

due to size of the file, it is consumpting more memory which leads to performance issue.
After checking in iis log, the download process is taking 42 mb and 64 mb each respectively.
Thanks in advance

Answer 1

A better option would be to use FileResult instead of ActionResult:

Using this method means you don't have to load the file/bytes in memory before serving.

public FileResult Download()
{
     var filePath = "file path in server";
     return new FilePathResult(Server.MapPath(filePath), "application/zip");
}

Edit: For larger files FilePathResult will also fail.

Your best bet is probably Response.TransmitFile() then. I've used this on larger files (GBs) and had no issues before

public ActionResult Download()
{

    var filePath = @"file path from server";

    Response.Clear();
    Response.ContentType = "application/octet-stream";
    Response.AppendHeader("Content-Disposition", "filename=" + filePath);

    Response.TransmitFile(filePath);

    Response.End();

    return Index();
}

From MSDN:

Writes the specified file directly to an HTTP response output stream, without buffering it in memory.