Issue #27787: Clean up weak references before checking for dangling threads

Lib/test/regrtest.py

@@ -1258,6 +1258,7 @@ class saved_test_environment:
     def __exit__(self, exc_type, exc_val, exc_tb):
         saved_values = self.saved_values
         del self.saved_values
+        support.gc_collect()  # Some resources use weak references
         for name, get, restore in self.resource_info():
             current = get()
             original = saved_values.pop(name)

Misc/NEWS

@@ -155,6 +155,9 @@ C API
 Tests
 -----
 
+- Issue #27787: Call gc.collect() before checking each test for "dangling
+  threads", since the dangling threads are weak references.
+
 - Issue #27369: In test_pyexpat, avoid testing an error message detail that
   changed in Expat 2.2.0.