Let trackref release classes defined at run time (#7922)

scrapy/utils/trackref.py

@@ -14,7 +14,6 @@ This library has a minimal performance impact.
 
 from __future__ import annotations
 
-from collections import defaultdict
 from operator import itemgetter
 from time import monotonic_ns
 from types import NoneType
@@ -28,8 +27,8 @@ if TYPE_CHECKING:
     from typing_extensions import Self
 
 
-live_refs: defaultdict[type, WeakKeyDictionary[object, float]] = defaultdict(
-    WeakKeyDictionary
+live_refs: WeakKeyDictionary[type, WeakKeyDictionary[object, float]] = (
+    WeakKeyDictionary()
 )
 
 
@@ -41,7 +40,11 @@ class object_ref:
 
     def __new__(cls, *args: Any, **kwargs: Any) -> Self:
         obj = object.__new__(cls)
-        live_refs[cls][obj] = monotonic_ns()
+        try:
+            refs = live_refs[cls]
+        except KeyError:
+            refs = live_refs[cls] = WeakKeyDictionary()
+        refs[obj] = monotonic_ns()
         return obj
 
 

tests/test_utils_trackref.py

@@ -124,3 +124,13 @@ def test_iter_all():
     o2 = Bar()  # noqa: F841
     o3 = Foo()
     assert set(trackref.iter_all("Foo")) == {o1, o3}
+
+
+def test_run_time_classes() -> None:
+    for _ in range(10):
+        base = type("Baz", (trackref.object_ref,), {})
+        base()
+    del base
+    garbage_collect()
+    assert not list(trackref.iter_all("Baz"))
+    assert sum(1 for cls in trackref.live_refs if cls.__name__ == "Baz") == 0