| the friendly display name 2005-12-17, 7:57 am |
| Following problem:
I want to stream a file to the client, but the logic takes too much CPU time
(100% in fact..) this is the code:
public class Download : System.Web.UI.Page
{
private byte[] buffer;
private AsyncCallback callback;
private Filestream fs;
private void Page_Load (object sender, System.Eventargs e)
{
fs = File.Open (....) // I won't bore you with the non interesting parts
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
Response.AddHeader("content-disposition", "attachment;
filename=blabla.exe");
Response.ContentType = "application/octet-stream";
fs.BeginRead(buffer, 0, 1024, callback, null);
}
void whencomplete (IAsyncResult Result)
{
int BytesRead = fs.EndRead(Result);
if (BytesRead > 0)
{
Response.BinaryWrite(buffer);
Response.Flush();
fs.BeginRead(buffer, 0, 1024, callback, null);
}
if (BytesRead == 0)
{
fs.Close();
Response.Close();
}
in private void InitializeComponent():
{
buffer = new byte[1024];
callback = new AsyncCallback (whencomplete);
}
---
This works, but it does take the whole CPU. If I add a sleep cycle in
whencomplete:
---
if (BytesRead > 0)
{
Response.BinaryWrite(buffer);
Response.Flush();
Thread.Sleep(100);
fs.BeginRead(buffer, 0, 1024, callback, null);
}
----
The CPU Utilization goes nearly to zero, but only with one running download.
I tried 3 downloads at the same time, and the CPU was again quite occupied.
What's the more effective way to stream? Is it even possible to stream,
without a high cpu utilization, since it's basicaly a .aspx site, which is
running in a loop?
|