Threading

I'm currently creating a socket cerver class, similar to Twisted for python. I have a simple socket server working now, but would like to extend it using threads. I've done a fair bit of research on threads in PHP in the past, but coming up to the conclusion that there is no way to have real multi threading in PHP. Would anybody here know of any way to use threads in PHP that I may have missed? I'm hoping to find a way that would work on most OS's without any major changes. Darren