reinitialize an Event's Condition with a regular lock (closes #25319)

Lib/test/lock_tests.py

@@ -388,6 +388,14 @@ class EventTests(BaseTestCase):
         b.wait_for_finished()
         self.assertEqual(results, [True] * N)
 
+    def test_reset_internal_locks(self):
+        evt = self.eventtype()
+        old_lock = evt._cond._lock
+        evt._reset_internal_locks()
+        new_lock = evt._cond._lock
+        self.assertIsNot(new_lock, old_lock)
+        self.assertIs(type(new_lock), type(old_lock))
+
 
 class ConditionTests(BaseTestCase):
     """

Lib/threading.py

@@ -496,7 +496,7 @@ class Event:
 
     def _reset_internal_locks(self):
         # private!  called by Thread._reset_internal_locks by _after_fork()
-        self._cond.__init__()
+        self._cond.__init__(Lock())
 
     def is_set(self):
         """Return true if and only if the internal flag is true."""

Misc/ACKS

@@ -1315,6 +1315,7 @@ Ryan Smith-Roberts
 Rafal Smotrzyk
 Eric Snow
 Dirk Soede
+Nir Soffer
 Paul Sokolovsky
 Evgeny Sologubov
 Cody Somerville

Misc/NEWS

@@ -100,6 +100,9 @@ Library
   submit a coroutine to a loop from another thread, returning a
   concurrent.futures.Future.  By Vincent Michel.
 
+- Issue #25319: When threading.Event is reinitialized, the underlying condition
+  should use a regular lock rather than a recursive lock.
+
 - Issue #25232: Fix CGIRequestHandler to split the query from the URL at the
   first question mark (?) rather than the last. Patch from Xiang Zhang.