Emulating traffic from a real logged access file

[socialvisionsbcn]

Our main site runs currently up to 1000 simultaneous users online (15 minutes session period). But its graphical content is high and it is heavily modified by products and plugins.

I have a cloned testing site for testing modifications before installing at live domain, but without real traffic I can not get any perception on server performance before the new code goes "live".

I would be interested in developing such a tool for simulating as good as posible (user browser caching of real users is hard to emulate) the response of the server for a real log of page requests. I mean, at least get the read-only simulation of the forum behaviour with the new code.

Has anyone gone inside this before? Any posible reference?

Best regards