alt Hacker News> Whether reference counting is a GC algorithm depends on how you define what GC is.
Pretty much all the high-performance GC/refcounting algorithms are hybrids in one form or the other; it's a spectrum of choices. https://dl.acm.org/doi/10.1145/1028976.1028982 explores this in some detail.
That is a classic paper and obviously I am aware of it.
However, if you have distinct names it is efficient to use them with distinct meanings.
Making "garbage collection" synonymous with "freeing memory" is bad, because it eliminates a means to distinguish various methods for freeing memory.
Like I have said, I consider useful to define "garbage collection" as any method of freeing memory where the memory is not freed as soon as possible (i.e. when a block is exited), but freeing is deferred to be performed at a later time, even as late as possible (i.e. when new memory allocation requests cannot be satisfied).
Indeed, many garbage collection algorithms use reference counts, where memory deallocation is deferred, but when I use the term "reference counting" without any other qualifier, I mean it in the sense in which it was originally defined in 1960, where the time when memory deallocation is run is predictable, exactly like for stack-allocated memory.
I prefer to write programs with well-defined worst-case behavior, so I normally prefer deterministic algorithms. Thus I always prefer to use reference counts instead of GC. I have never encountered a case when avoiding reference cycles was difficult.