In his previous post ("PHP was meant to die") the point was made that PHP isn't really designed as a language to handle long running processes very well. It's made to handle a few operations and then die at the end of the request. In this follow up post he talks more about using PHP for long running processes and a library that could help.

Yes, I already acknowledged that PHP has a garbage collection implementation starting 5.3.0 and up (opt-in or opt-out, that’s not the problem). I also acknowledge that garbage collection works, and is able to take care of most circular references just fine. [...] Anyway, as previously stated too, garbage collection is a great thing, but not enough for PHP. It’s a borrowed feature that does not play well with old fundamental decisions inherited from the original design. Garbage collection is not a magical solution for every problem, like many tried to argue about. Let’s illustrate with another example.

His example uses the React PHP library (a non-blocking I/O platform) to handle a lot of incoming data to a port and report back some memory usage and limit settings. He explains a bit about what's happening and shares the results of the test, including the end result - a fatal error when the memory limit was hit. He still comes to the same conclusion, ultimately...PHP is just not the language to use for long-running processes that do any large amount of work.