https://github.com/python/cpython/commit/a2c1657cab8daed6cf6236d67967372de7442d8b
commit: a2c1657cab8daed6cf6236d67967372de7442d8b
branch: main
author: Pieter Eendebak <[email protected]>
committer: JelleZijlstra <[email protected]>
date: 2026-05-09T19:52:52-07:00
summary:
gh-149436: Speed up inspect.getattr_static for the common-metaclass case
(#149437)
Consecutive MRO entries usually share their metaclass, so call
_shadowed_dict at most once per distinct metaclass.
files:
A Misc/NEWS.d/next/Library/2026-05-08-14-24-16.gh-issue-149436.dEV02X.rst
M Lib/inspect.py
diff --git a/Lib/inspect.py b/Lib/inspect.py
index a96b3dc954ef0c..3e85625cd30263 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1709,9 +1709,13 @@ def _check_instance(obj, attr):
def _check_class(klass, attr):
+ last_meta = None
for entry in _static_getmro(klass):
- if _shadowed_dict(type(entry)) is _sentinel and attr in entry.__dict__:
- return entry.__dict__[attr]
+ meta = type(entry)
+ if meta is last_meta or _shadowed_dict(meta) is _sentinel:
+ last_meta = meta
+ if attr in entry.__dict__:
+ return entry.__dict__[attr]
return _sentinel
@@ -1743,6 +1747,9 @@ def _shadowed_dict(klass):
# destroyed, and the dynamically created classes happen to be the only
# objects that hold strong references to other objects that take up a
# significant amount of memory.
+ # Fast path: `type` is the dominant caller; result is always _sentinel.
+ if klass is type:
+ return _sentinel
return _shadowed_dict_from_weakref_mro_tuple(
*[make_weakref(entry) for entry in _static_getmro(klass)]
)
diff --git
a/Misc/NEWS.d/next/Library/2026-05-08-14-24-16.gh-issue-149436.dEV02X.rst
b/Misc/NEWS.d/next/Library/2026-05-08-14-24-16.gh-issue-149436.dEV02X.rst
new file mode 100644
index 00000000000000..401cf044e1514f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-05-08-14-24-16.gh-issue-149436.dEV02X.rst
@@ -0,0 +1 @@
+Improve performance of :meth:`inspect.getattr_static`.
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