https://github.com/python/cpython/commit/34b85ef26c44bbbd8a05d3e7dee6997b3623aab0
commit: 34b85ef26c44bbbd8a05d3e7dee6997b3623aab0
branch: main
author: Pieter Eendebak <[email protected]>
committer: erlend-aasland <[email protected]>
date: 2024-12-30T18:18:42+01:00
summary:
gh-128118: Speed up copy.copy with fast lookup for atomic and container types
(#128119)
files:
A Misc/NEWS.d/next/Library/2024-12-20-10-57-10.gh-issue-128118.mYak8i.rst
M Lib/copy.py
diff --git a/Lib/copy.py b/Lib/copy.py
index f27e109973cfb7..c64fc0761793f5 100644
--- a/Lib/copy.py
+++ b/Lib/copy.py
@@ -67,13 +67,15 @@ def copy(x):
cls = type(x)
- copier = _copy_dispatch.get(cls)
- if copier:
- return copier(x)
+ if cls in _copy_atomic_types:
+ return x
+ if cls in _copy_builtin_containers:
+ return cls.copy(x)
+
if issubclass(cls, type):
# treat it as a regular class:
- return _copy_immutable(x)
+ return x
copier = getattr(cls, "__copy__", None)
if copier is not None:
@@ -98,23 +100,12 @@ def copy(x):
return _reconstruct(x, None, *rv)
-_copy_dispatch = d = {}
-
-def _copy_immutable(x):
- return x
-for t in (types.NoneType, int, float, bool, complex, str, tuple,
+_copy_atomic_types = {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):
- d[t] = _copy_immutable
-
-d[list] = list.copy
-d[dict] = dict.copy
-d[set] = set.copy
-d[bytearray] = bytearray.copy
-
-del d, t
+ weakref.ref, super}
+_copy_builtin_containers = {list, dict, set, bytearray}
def deepcopy(x, memo=None, _nil=[]):
"""Deep copy operation on arbitrary Python objects.
diff --git
a/Misc/NEWS.d/next/Library/2024-12-20-10-57-10.gh-issue-128118.mYak8i.rst
b/Misc/NEWS.d/next/Library/2024-12-20-10-57-10.gh-issue-128118.mYak8i.rst
new file mode 100644
index 00000000000000..bc2898edfda721
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-12-20-10-57-10.gh-issue-128118.mYak8i.rst
@@ -0,0 +1,2 @@
+Improve performance of :func:`copy.copy` by 30% via
+a fast path for atomic types and container types.
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