I have heard about making cpu procesesses which does the same job. AFAIK it is called forking in linux. Can you give some references how it is done in linux,php?
You might want to take a look at the PHP manual:
http://www.php.net/pcntl
There is a function for linux called, of all things, pcntl_fork(). Very useful in some situations. If only it worked on Windows too...