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gh-132657: Make deepcopy and copy scale with free-threading #138429

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Merged
merged 4 commits into from
Sep 4, 2025
+9 −8
Merged

gh-132657: Make deepcopy and copy scale with free-threading #138429

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8601540
Make deepcopy and copy scale with free-threading
eendebakpt Sep 3, 2025
08f90f5
📜🤖 Added by blurb_it.
blurb-it[bot] Sep 3, 2025
4c7c42b
Update Lib/copy.py
eendebakpt Sep 4, 2025
9c37bcf
Merge branch 'main' into copy_deepcopy_ft
eendebakpt Sep 4, 2025
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16 changes: 8 additions & 8 deletions Lib/copy.py
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Original file line number Diff line number Diff line change
Expand Up @@ -100,14 +100,14 @@ def copy(x):
return _reconstruct(x, None, *rv)


_copy_atomic_types = {types.NoneType, int, float, bool, complex, str, tuple,
_copy_atomic_types = frozenset({types.NoneType, int, float, bool, complex, str, tuple,
bytes, frozenset, type, range, slice, property,
types.BuiltinFunctionType, types.EllipsisType,
types.NotImplementedType, types.FunctionType, types.CodeType,
weakref.ref, super}
_copy_builtin_containers = {list, dict, set, bytearray}
weakref.ref, super})
_copy_builtin_containers = frozenset({list, dict, set, bytearray})

def deepcopy(x, memo=None, _nil=[]):
def deepcopy(x, memo=None):
"""Deep copy operation on arbitrary Python objects.

See the module's __doc__ string for more info.
Expand All @@ -122,8 +122,8 @@ def deepcopy(x, memo=None, _nil=[]):
if memo is None:
memo = {}
else:
y = memo.get(d, _nil)
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I'm surprised, but replacing _nil with None works well. It seems like memo values are never None.

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Correct, the only values set are integers (id of objects)

if y is not _nil:
y = memo.get(d, None)
if y is not None:
return y

copier = _deepcopy_dispatch.get(cls)
Expand Down Expand Up @@ -162,9 +162,9 @@ def deepcopy(x, memo=None, _nil=[]):
_keep_alive(x, memo) # Make sure x lives at least as long as d
return y

_atomic_types = {types.NoneType, types.EllipsisType, types.NotImplementedType,
_atomic_types = frozenset({types.NoneType, types.EllipsisType, types.NotImplementedType,
int, float, bool, complex, bytes, str, types.CodeType, type, range,
types.BuiltinFunctionType, types.FunctionType, weakref.ref, property}
types.BuiltinFunctionType, types.FunctionType, weakref.ref, property})

_deepcopy_dispatch = d = {}

Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2025-09-03-09-03-11.gh-issue-132657.cbAIDh.rst
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@@ -0,0 +1 @@
Improve the scaling of :func:`copy.copy` and :func:`copy.deepcopy` in the free-threading build.
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