Using comet with PHP?

Question

I was thinking of implementing real time chat using a PHP backend, but I ran across this comment on a site discussing comet:

My understanding is that

Answer 1

You'll have a hard time implementing comet in PHP, just because of it's inherent single-threaded-ness.

Check out Websync On-Demand - the service lets you integrate PHP via server-side publishing, offloading the heavy concurrent connection stuff, and will let you create a real-time chat app in no time.