perf: lazily calculate _key in Version#989
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henryiii
reviewed
Nov 25, 2025
Contributor
|
There's also diff --git a/src/packaging/version.py b/src/packaging/version.py
index 5261cd5..319ce66 100644
--- a/src/packaging/version.py
+++ b/src/packaging/version.py
@@ -9,6 +9,7 @@
from __future__ import annotations
+import functools
import re
from typing import Any, Callable, NamedTuple, SupportsInt, Tuple, Union
@@ -185,7 +186,6 @@ class Version(_BaseVersion):
_regex = re.compile(r"^\s*" + VERSION_PATTERN + r"\s*$", re.VERBOSE | re.IGNORECASE)
_version: _Version
- __key: CmpKey | None
def __init__(self, version: str) -> None:
"""Initialize a Version object.
@@ -216,18 +216,16 @@ class Version(_BaseVersion):
# Key which will be used for sorting
self.__key = None
- @property
+ @functools.cached_property
def _key(self) -> CmpKey:
- if self.__key is None:
- self.__key = _cmpkey(
- self._version.epoch,
- self._version.release,
- self._version.pre,
- self._version.post,
- self._version.dev,
- self._version.local,
- )
- return self.__key
+ return _cmpkey(
+ self._version.epoch,
+ self._version.release,
+ self._version.pre,
+ self._version.post,
+ self._version.dev,
+ self._version.local,
+ )
def __repr__(self) -> str:
"""A representation of the Version that shows all internal state. |
_key in Version_key in Version
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Author
|
I took a look at cached property and there are too many nuances, dependencies, and behavior changes for me to be comfortable using it: https://docs.python.org/3/library/functools.html#functools.cached_property |
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henryiii
approved these changes
Nov 26, 2025
Contributor
|
Saves about 15% (total time) if |
Contributor
|
After this and all the recent optimizations (regex, etc), loading every version from PyPI takes 82.4 seconds. On 25.0, it takes 116.1 seconds. (Python 3.14) |
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Inspired by #987 I investigated if calling
_cmpkeyto calculate_keyon everyVersioninitialization made sense.At least for pip,
_keyis only accessed on less than 30% ofVersionobjects ever created, with longer resolutions going down to below 20%, so precalculating_keywith_cmpkeyis doing work that's often not needed._versioncould also be made lazy, but at least for pip_versionis accessed on 100% of allVersionobjects.