What I'm looking to do is load in some data from a database or from memcache asynchronously.
I know, I know. "PHP doesn't support threading".
But what about register_tick_function? Isn't that indeed threading?
Has anyone done any kind of predictive preload or really any background processing utilizing register_tick_function?
PHP certainly can support threading. Loading data from a SQL/NoSQL database in parallel is definitely a possibility. See the PHP manual, examples found in github and pecl packages.
Please note, the documentation did state that this is part of the core, this is ( my ) human error. You must install pthreads with a thread-safe version of php, it can be installed from pecl ( windows incuded, dlls @ http://windows.php.net/downloads/pecl/releases/pthreads ). Apologies.