[jcampbell1]

PHP is reference counted, so memory is typically freed as soon as an object is no longer needed. Cycles are the exception which can cause memory leaks, so in version 5.3 php added a cycle collector, which reads every object in memory and very occasionally deletes objects that are disconnected and have greater than zero reference counts (cycles).

In my opinion, the php cycle collector is a pointless waste of time. In objective-c, apple just let's the memory leak by default, and they give you tools to find the leaks, and then you modify the code to break the cycles.

There is no need to turn cycle collection back on at the end of the program, because OS frees the memory at program termination.

[innocenat]

I agree that cycle collector is pointless waste of time. Most script runs short enough that the memory leak doesn't really matter.

But for long running script, it's either cycle collector, or add support for weak reference. But IMO, due to how reference are stored in PHP, and to my limited knowledge of PHP core, I am quite sure cycle collector are more beneficial in both developer time and usefulness. (Not every programmers know how to manage reference cycle)

[vertex-four]

I'll note that in common usage, PHP does not exit entirely at the end of every HTTP request. (By default, PHP-FPM never exits between requests.) You would, at the least, have to keep track of all live objects and delete them at the end of each request... which sounds like a garbage collector to me.