Merge pull request #12080 from mauritsvanrees/maurits-issue-12079-slo…

…w-importlib
pypa · Jun 16, 2023 · 5190ef7 · 5190ef7
2 parents 8a1eea4 + 6aef932
commit 5190ef7
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diff --git a/news/12079.bugfix.rst b/news/12079.bugfix.rst
@@ -0,0 +1 @@
+Fix slowness when using ``importlib.metadata`` (the default way for pip to read metadata in Python 3.11+) and there is a large overlap between already installed and to-be-installed packages.
diff --git a/src/pip/_internal/resolution/resolvelib/candidates.py b/src/pip/_internal/resolution/resolvelib/candidates.py
@@ -341,6 +341,7 @@ def __init__(
         self.dist = dist
         self._ireq = _make_install_req_from_dist(dist, template)
         self._factory = factory
+        self._version = None
 
         # This is just logging some messages, so we can do it eagerly.
         # The returned dist would be exactly the same as self.dist because we
@@ -376,7 +377,9 @@ def name(self) -> str:
 
     @property
     def version(self) -> CandidateVersion:
-        return self.dist.version
+        if self._version is None:
+            self._version = self.dist.version
+        return self._version
 
     @property
     def is_editable(self) -> bool: