Interesting, I saw an article a while ago about how you can achieve async programming with PHP by using shell_exec(). The problem is though, for people writing software or applications for others(like a CMS or forumware), they have to compensate for client users running with shared hosts. Shared hosts do not normally enable shell_exec() unfortunately. I wonder how Amy Unruh’s techniques works though, hopefully it does not involve anything that requires shell/linux command execution.