5 ms·

Re: "it's well understood reference counting is garbage collection". I think this might just be a terminology thing. There appear to be two ways the terms are

Re: "it's well understood reference counting is garbage collection". I think this might just be a terminology thing. There appear to be two ways the terms are categorized: 1. "reference counting" and "garbage collection" are two types of automatic memory management/reclamation. 2. "reference counting" and "tracing garbage collection" are two types of garbage collection. I think mbrodersen is using #1. (Back in the 90s and 2000s I feel like #1 was much more prevalent. But #2 seems to have gained popularity since then. My theory is that whoever started writing the Wikipedia content for this stuff picked #2.)

rowanG077 4y ago
I never understand why people refer to reference counting as garbage collection. It waters down the term so much it becomes essentially useless. Because under that assumptions basically every language has garbage collection in some shape or form.
- jstanley 4y ago
  C doesn't have garbage collection. Furthermore, pretty much every language has I/O, but that doesn't make the term useless.
- tsimionescu 4y ago
  They do it because they serve the same purpose, though with different trade-offs. Note that this mostly reflects automatic reference counting, like you have in Python or Swift, not so much manual reference counting like std::shared_ptr or Rc.
- pjmlp 4y ago
  Because we have studied the literature instead of what a random dude in tells at a coffee https://gchandbook.org/ https://gchandbook.org/ https://www.sigplan.org/ https://www.sigplan.org/ https://ieeexplore.ieee.org/Xplore/home.jsp https://ieeexplore.ieee.org/Xplore/home.jsp
  - rowanG077 4y ago
    Nice appeal to authority instead of trying to engage in a meaningful way.
    - pjmlp 4y ago
      When one is open to learning, the best path to enlightenment is to use the same books as the Wizards on the tower of knowledge.
tsimionescu 4y ago
I think this is actually common in the literature, it has nothing to do with Wikipedia. Consider that Python is commonly described as a GC language, though it has always mostly relied on automatic reference counting to free objects (it does have a tracing GC as well to handle cycles, but I'm not sure if it always did).
- int_19h 4y ago
  I would argue that what matters is the observable behavior. In Python, regardless of how the actual cleanup is distributed between ARC and GC, the behavior that programmer sees is that all unused memory gets cleaned up eventually. So, it makes sense to group it with languages that provide the same guarantee.
bjourne 4y ago
I think it's more of an industry vs. academia kind of thing. In the mid-90's before Java was released automatic memory management was mostly unknown to the unwashed masses. So garbage collection became synonymous to whatever Java was doing. However, The Garbage Collection Handbook originally published in 1996 defines garbage collection as: "All garbage collection schemes are based on one of four fundamental approaches; mark-sweep collection, copying collection, mark-compact collection or reference counting." So that's an example of terminology #2.
mbrodersen 4y ago
Yep. The compiler generates code that works the same way that an experienced C programmer would hand optimise alloc/free calls and manually keep track of shared data by increasing/reducing a reference counter. There is no separate mark/sweep or whatever step.

rowanG077 4y ago

I never understand why people refer to reference counting as garbage collection. It waters down the term so much it becomes essentially useless. Because under that assumptions basically every language has garbage collection in some shape or form.

jstanley 4y ago
C doesn't have garbage collection. Furthermore, pretty much every language has I/O, but that doesn't make the term useless.
tsimionescu 4y ago
They do it because they serve the same purpose, though with different trade-offs. Note that this mostly reflects automatic reference counting, like you have in Python or Swift, not so much manual reference counting like std::shared_ptr or Rc.
pjmlp 4y ago
Because we have studied the literature instead of what a random dude in tells at a coffee https://gchandbook.org/ https://gchandbook.org/ https://www.sigplan.org/ https://www.sigplan.org/ https://ieeexplore.ieee.org/Xplore/home.jsp https://ieeexplore.ieee.org/Xplore/home.jsp
- rowanG077 4y ago
  Nice appeal to authority instead of trying to engage in a meaningful way.
  - pjmlp 4y ago
    When one is open to learning, the best path to enlightenment is to use the same books as the Wizards on the tower of knowledge.

tsimionescu 4y ago

I think this is actually common in the literature, it has nothing to do with Wikipedia. Consider that Python is commonly described as a GC language, though it has always mostly relied on automatic reference counting to free objects (it does have a tracing GC as well to handle cycles, but I'm not sure if it always did).

int_19h 4y ago
I would argue that what matters is the observable behavior. In Python, regardless of how the actual cleanup is distributed between ARC and GC, the behavior that programmer sees is that all unused memory gets cleaned up eventually. So, it makes sense to group it with languages that provide the same guarantee.

bjourne 4y ago

I think it's more of an industry vs. academia kind of thing. In the mid-90's before Java was released automatic memory management was mostly unknown to the unwashed masses. So garbage collection became synonymous to whatever Java was doing. However, The Garbage Collection Handbook originally published in 1996 defines garbage collection as: "All garbage collection schemes are based on one of four fundamental approaches; mark-sweep collection, copying collection, mark-compact collection or reference counting." So that's an example of terminology #2.

mbrodersen 4y ago

Yep. The compiler generates code that works the same way that an experienced C programmer would hand optimise alloc/free calls and manually keep track of shared data by increasing/reducing a reference counter. There is no separate mark/sweep or whatever step.