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iritkatriel merged 6 commits into from
Oct 11, 2024
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gh-119786: Move garbage collection doc from devguide to InternalDocs #125282

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move gc doc from devguide, convert to markdown
iritkatriel Oct 10, 2024
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iritkatriel Oct 10, 2024
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iritkatriel Oct 10, 2024
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iritkatriel Oct 10, 2024
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Apply suggestions from code review 
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Jacob Coffee <jacob@z7x.org>
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@iritkatriel @AA-Turner @JacobCoffee
3 people authored Oct 11, 2024
commit ea21be8f5cf4da43fe37d40ed0d9e9e0996b70fd
18 changes: 9 additions & 9 deletions InternalDocs/garbage_collector.md
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Expand Up @@ -12,11 +12,11 @@ a local variable in some C function. When an object’s reference count becomes
the object is deallocated. If it contains references to other objects, their
reference counts are decremented. Those other objects may be deallocated in turn, if
this decrement makes their reference count become zero, and so on. The reference
count field can be examined using the ``sys.getrefcount`` function (notice that the
count field can be examined using the ``sys.getrefcount()`` function (notice that the
value returned by this function is always 1 more as the function also has a reference
to the object when called):

```
```pycon
>>> x = object()
>>> sys.getrefcount(x)
2
Expand All @@ -31,7 +31,7 @@ to the object when called):
The main problem with the reference counting scheme is that it does not handle reference
cycles. For instance, consider this code:

```
```pycon
>>> container = []
>>> container.append(container)
>>> sys.getrefcount(container)
Expand Down Expand Up @@ -198,7 +198,7 @@ the case of a circular linked list which has one link referenced by a
variable ``A``, and one self-referencing object which is completely
unreachable:

```
```pycon
>>> import gc

>>> class Link:
Expand Down Expand Up @@ -242,7 +242,7 @@ interpreter will not modify the real reference count field.
![gc-image1](images/python-cyclic-gc-1-new-page.png)

The GC then iterates over all containers in the first list and decrements by one the
``gc_ref`` field of any other object that container is referencing. Doing
`gc_ref` field of any other object that container is referencing. Doing
this makes use of the ``tp_traverse`` slot in the container class (implemented
using the C API or inherited by a superclass) to know what objects are referenced by
each container. After all the objects have been scanned, only the objects that have
Expand Down Expand Up @@ -383,10 +383,10 @@ examined, then generation 1 is examined as well. With generation 2,
things are a bit more complicated; see
[Collecting the oldest generation](#Collecting-the-oldest-generation) for
more information. These thresholds can be examined using the
[`gc.get_threshold`](https://docs.python.org/3/library/gc.html#gc.get_threshold)
[`gc.get_threshold()`](https://docs.python.org/3/library/gc.html#gc.get_threshold)
function:

```
```pycon
>>> import gc
>>> gc.get_threshold()
(700, 10, 10)
Expand All @@ -396,7 +396,7 @@ The content of these generations can be examined using the
``gc.get_objects(generation=NUM)`` function and collections can be triggered
specifically in a generation by calling ``gc.collect(generation=NUM)``.

```
```pycon
>>> import gc
>>> class MyObj:
... pass
Expand Down Expand Up @@ -535,7 +535,7 @@ The garbage collector module provides the Python function ``is_tracked(obj)``, w
the current tracking status of the object. Subsequent garbage collections may change the
tracking status of the object.

```
```pycon
>>> gc.is_tracked(0)
False
>>> gc.is_tracked("a")
Expand Down