Optimize provider's is_backtrack_cause by caching resolved names

news/10621.feature.rst

@@ -0,0 +1 @@
+Optimize performance of conflict cause resolution while the dependency resolver backtracks.

src/pip/_internal/resolution/resolvelib/provider.py

@@ -7,6 +7,8 @@
     Iterator,
     Mapping,
     Sequence,
+    Set,
+    Tuple,
     TypeVar,
     Union,
 )
@@ -100,6 +102,7 @@ def __init__(
         self._upgrade_strategy = upgrade_strategy
         self._user_requested = user_requested
         self._known_depths: Dict[str, float] = collections.defaultdict(lambda: math.inf)
+        self._backtrack_cause_name_collections: Dict[Tuple[int, ...], Set[str]] = {}
 
     def identify(self, requirement_or_candidate: Union[Requirement, Candidate]) -> str:
         return requirement_or_candidate.name
@@ -236,13 +239,28 @@ def get_dependencies(self, candidate: Candidate) -> Sequence[Requirement]:
         with_requires = not self._ignore_dependencies
         return [r for r in candidate.iter_dependencies(with_requires) if r is not None]
 
-    @staticmethod
     def is_backtrack_cause(
-        identifier: str, backtrack_causes: Sequence["PreferenceInformation"]
+        self, identifier: str, backtrack_causes: Sequence["PreferenceInformation"]
     ) -> bool:
-        for backtrack_cause in backtrack_causes:
-            if identifier == backtrack_cause.requirement.name:
-                return True
-            if backtrack_cause.parent and identifier == backtrack_cause.parent.name:
-                return True
-        return False
+        return identifier in self._get_causes_set(backtrack_causes)
+
+    def _get_causes_set(
+        self,
+        backtrack_causes: Sequence["PreferenceInformation"],
+    ) -> Set[str]:
+        backtrack_causes_collection_key = tuple(id(c) for c in backtrack_causes)
+        cached_names = self._backtrack_cause_name_collections.get(
+            backtrack_causes_collection_key
+        )
+        if cached_names is None:
+            self._backtrack_cause_name_collections.clear()
+            cached_names = set()
+            for backtrack_cause in backtrack_causes:
+                cached_names.add(backtrack_cause.requirement.name)
+                parent = backtrack_cause.parent
+                if parent:
+                    cached_names.add(parent.name)
+            self._backtrack_cause_name_collections[
+                backtrack_causes_collection_key
+            ] = cached_names
+        return cached_names