generator is borrowed

RustPython · youknowone · Feb 1, 2026 · Jan 30, 2026 · Jan 30, 2026 · Jan 30, 2026
commit 7258a4ae926a107bc2c4076b5b0e83a2a25c0e90
diff --git a/Lib/test/test_asyncgen.py b/Lib/test/test_asyncgen.py
@@ -1026,7 +1026,6 @@ async def run():
         fut.cancel()
         self.loop.run_until_complete(asyncio.sleep(0.01))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; gc_collect doesn't finalize async generators
     def test_async_gen_asyncio_gc_aclose_09(self):
         DONE = 0
 
@@ -1513,7 +1512,6 @@ async def main():
         self.assertIn('an error occurred during closing of asynchronous generator',
                       message['message'])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; gc_collect doesn't finalize async generators, different cleanup path
     def test_async_gen_asyncio_shutdown_exception_02(self):
         messages = []
 

diff --git a/Lib/test/test_asyncio/test_free_threading.py b/Lib/test/test_asyncio/test_free_threading.py
@@ -189,10 +189,6 @@ def tearDown(self):
     def factory(self, loop, coro, **kwargs):
         return asyncio.tasks._PyTask(coro, loop=loop, **kwargs)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference timing issue
-    def test_task_different_thread_finalized(self):
-        return super().test_task_different_thread_finalized()
-
     @unittest.skip("TODO: RUSTPYTHON; hangs - Python _current_tasks dict not thread-safe")
     def test_all_tasks_race(self):
         return super().test_all_tasks_race()
@@ -228,10 +224,6 @@ class TestEagerPyFreeThreading(TestPyFreeThreading):
     def factory(self, loop, coro, eager_start=True, **kwargs):
         return asyncio.tasks._PyTask(coro, loop=loop, **kwargs, eager_start=eager_start)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference timing issue
-    def test_task_different_thread_finalized(self):
-        return super().test_task_different_thread_finalized()
-
     @unittest.skip("TODO: RUSTPYTHON; hangs - Python _current_tasks dict not thread-safe")
     def test_all_tasks_race(self):
         return super().test_all_tasks_race()

diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
@@ -1078,7 +1078,6 @@ def test_eof_feed_when_closing_writer(self):
 
         self.assertEqual(messages, [])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC finalization timing issue
     def test_unclosed_resource_warnings(self):
         async def inner(httpd):
             rd, wr = await asyncio.open_connection(*httpd.address)

diff --git a/Lib/test/test_concurrent_futures/test_as_completed.py b/Lib/test/test_concurrent_futures/test_as_completed.py
@@ -72,7 +72,6 @@ def test_duplicate_futures(self):
         ]
         self.assertEqual(len(completed), 1)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference not collected
     def test_free_reference_yielded_future(self):
         # Issue #14406: Generator should not keep references
         # to finished futures.

diff --git a/Lib/test/test_concurrent_futures/test_init.py b/Lib/test/test_concurrent_futures/test_init.py
@@ -136,11 +136,9 @@ def _test(self, test_class):
 
         self.assertEqual(_resource_tracker._exitcode, 0)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; resource tracker exit code mismatch
     def test_spawn(self):
         self._test(ProcessPoolSpawnFailingInitializerTest)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; resource tracker exit code mismatch
     @support.skip_if_sanitizer("TSAN doesn't support threads after fork", thread=True)
     def test_forkserver(self):
         self._test(ProcessPoolForkserverFailingInitializerTest)

diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
@@ -837,15 +837,15 @@ class C(object):
         v[x] = y
         self.assertNotIn(x, u)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
+
     def test_copy_weakkeydict(self):
         self._check_copy_weakdict(weakref.WeakKeyDictionary)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
+
     def test_copy_weakvaluedict(self):
         self._check_copy_weakdict(weakref.WeakValueDictionary)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
+
     def test_deepcopy_weakkeydict(self):
         class C(object):
             def __init__(self, i):
@@ -866,7 +866,7 @@ def __init__(self, i):
         support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
+
     def test_deepcopy_weakvaluedict(self):
         class C(object):
             def __init__(self, i):

diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
@@ -1076,7 +1076,6 @@ def do_close(g):
             g.close()
         self._check_generator_cleanup_exc_state(do_close)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC generator cleanup timing
     def test_generator_del_cleanup_exc_state(self):
         def do_del(g):
             g = None

diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
@@ -3282,7 +3282,6 @@ def test_select_unbuffered(self):
         finally:
             p.wait()
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC Popen.__del__ timing
     def test_zombie_fast_process_del(self):
         # Issue #12650: on Unix, if Popen.__del__() was called before the
         # process exited, it wouldn't be added to subprocess._active, and would
@@ -3307,7 +3306,6 @@ def test_zombie_fast_process_del(self):
             # check that p is in the active processes list
             self.assertIn(ident, [id(o) for o in subprocess._active])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC Popen.__del__ timing
     def test_leak_fast_process_del_killed(self):
         # Issue #12650: on Unix, if Popen.__del__() was called before the
         # process exited, and the process got killed by a signal, it would never

diff --git a/Lib/test/test_unittest/test_suite.py b/Lib/test/test_unittest/test_suite.py
@@ -374,11 +374,9 @@ def test_nothing(self):
         self.assertEqual(suite._tests, [None])
         self.assertIsNone(wref())
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC test not collected after run
     def test_garbage_collect_test_after_run_BaseTestSuite(self):
         self.assert_garbage_collect_test_after_run(unittest.BaseTestSuite)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC test not collected after run
     def test_garbage_collect_test_after_run_TestSuite(self):
         self.assert_garbage_collect_test_after_run(unittest.TestSuite)
 

diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
@@ -1368,7 +1368,6 @@ def test_weak_keyed_len_race(self):
     def test_weak_valued_len_race(self):
         self.check_len_race(weakref.WeakValueDictionary, lambda k: (1, k))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
     def test_weak_values(self):
         #
         #  This exercises d.copy(), d.items(), d[], del d[], len(d).
@@ -1401,7 +1400,6 @@ def test_weak_values(self):
         gc_collect()  # For PyPy or other GCs.
         self.assertRaises(KeyError, dict.__getitem__, 2)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
     def test_weak_keys(self):
         #
         #  This exercises d.copy(), d.items(), d[] = v, d[], del d[],
@@ -1767,7 +1765,6 @@ def test_weak_valued_dict_update(self):
             self.assertEqual(list(d.keys()), [kw])
             self.assertEqual(d[kw], o)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
     def test_weak_valued_union_operators(self):
         a = C()
         b = C()
@@ -1820,7 +1817,6 @@ def test_weak_keyed_delitem(self):
         self.assertEqual(len(d), 1)
         self.assertEqual(list(d.keys()), [o2])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; weakref callback not fired immediately by gc_collect
     def test_weak_keyed_union_operators(self):
         o1 = C()
         o2 = C()

diff --git a/Lib/test/test_weakset.py b/Lib/test/test_weakset.py
@@ -69,7 +69,6 @@ def test_contains(self):
         support.gc_collect()  # For PyPy or other GCs.
         self.assertNotIn(ustr('F'), self.fs)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference not collected
     def test_union(self):
         u = self.s.union(self.items2)
         for c in self.letters:
@@ -92,7 +91,6 @@ def test_or(self):
         self.assertEqual(self.s | set(self.items2), i)
         self.assertEqual(self.s | frozenset(self.items2), i)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference not collected
     def test_intersection(self):
         s = WeakSet(self.letters)
         i = s.intersection(self.items2)
@@ -130,7 +128,6 @@ def test_sub(self):
         self.assertEqual(self.s - set(self.items2), i)
         self.assertEqual(self.s - frozenset(self.items2), i)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; GC weak reference not collected
     def test_symmetric_difference(self):
         i = self.s.symmetric_difference(self.items2)
         for c in self.letters:

diff --git a/crates/vm/src/builtins/asyncgenerator.rs b/crates/vm/src/builtins/asyncgenerator.rs
@@ -513,9 +513,7 @@ impl PyAsyncGenAThrow {
     ) -> PyResult {
         match self.state.load() {
             AwaitableState::Closed => {
-                return Err(
-                    vm.new_runtime_error("cannot reuse already awaited aclose()/athrow()")
-                );
+                return Err(vm.new_runtime_error("cannot reuse already awaited aclose()/athrow()"));
             }
             AwaitableState::Init => {
                 if self.ag.running_async.load() {
@@ -816,6 +814,12 @@ impl Destructor for PyAsyncGen {
     }
 }
 
+impl Drop for PyAsyncGen {
+    fn drop(&mut self) {
+        self.inner.frame().clear_generator();
+    }
+}
+
 pub fn init(ctx: &Context) {
     PyAsyncGen::extend_class(ctx, ctx.types.async_generator);
     PyAsyncGenASend::extend_class(ctx, ctx.types.async_generator_asend);

diff --git a/crates/vm/src/builtins/coroutine.rs b/crates/vm/src/builtins/coroutine.rs
@@ -222,6 +222,12 @@ impl IterNext for PyCoroutineWrapper {
     }
 }
 
+impl Drop for PyCoroutine {
+    fn drop(&mut self) {
+        self.inner.frame().clear_generator();
+    }
+}
+
 pub fn init(ctx: &Context) {
     PyCoroutine::extend_class(ctx, ctx.types.coroutine_type);
     PyCoroutineWrapper::extend_class(ctx, ctx.types.coroutine_wrapper_type);

diff --git a/crates/vm/src/builtins/frame.rs b/crates/vm/src/builtins/frame.rs
@@ -153,7 +153,7 @@ impl Frame {
 impl Py<Frame> {
     #[pygetset]
     fn f_generator(&self) -> Option<PyObjectRef> {
-        self.generator.lock().clone()
+        self.generator.to_owned()
     }
 
     #[pygetset]

diff --git a/crates/vm/src/builtins/function.rs b/crates/vm/src/builtins/function.rs
@@ -531,19 +531,19 @@ impl Py<PyFunction> {
             (true, false) => {
                 let obj = PyGenerator::new(frame.clone(), self.__name__(), self.__qualname__())
                     .into_pyobject(vm);
-                frame.set_generator(obj.clone());
+                frame.set_generator(&obj);
                 Ok(obj)
             }
             (false, true) => {
                 let obj = PyCoroutine::new(frame.clone(), self.__name__(), self.__qualname__())
                     .into_pyobject(vm);
-                frame.set_generator(obj.clone());
+                frame.set_generator(&obj);
                 Ok(obj)
             }
             (true, true) => {
                 let obj = PyAsyncGen::new(frame.clone(), self.__name__(), self.__qualname__())
                     .into_pyobject(vm);
-                frame.set_generator(obj.clone());
+                frame.set_generator(&obj);
                 Ok(obj)
             }
             (false, false) => vm.run_frame(frame),

diff --git a/crates/vm/src/builtins/generator.rs b/crates/vm/src/builtins/generator.rs
@@ -140,6 +140,12 @@ impl IterNext for PyGenerator {
     }
 }
 
+impl Drop for PyGenerator {
+    fn drop(&mut self) {
+        self.inner.frame().clear_generator();
+    }
+}
+
 pub fn init(ctx: &Context) {
     PyGenerator::extend_class(ctx, ctx.types.generator_type);
 }
diff --git a/crates/vm/src/frame.rs b/crates/vm/src/frame.rs
@@ -15,6 +15,7 @@ use crate::{
     coroutine::Coro,
     exceptions::ExceptionCtor,
     function::{ArgMapping, Either, FuncArgs},
+    object::PyAtomicBorrow,
     object::{Traverse, TraverseFn},
     protocol::{PyIter, PyIterReturn},
     scope::Scope,
@@ -85,8 +86,10 @@ pub struct Frame {
     pub trace_lines: PyMutex<bool>,
     pub trace_opcodes: PyMutex<bool>,
     pub temporary_refs: PyMutex<Vec<PyObjectRef>>,
-    /// Back-reference to owning generator/coroutine/async generator
-    pub generator: PyMutex<Option<PyObjectRef>>,
+    /// Back-reference to owning generator/coroutine/async generator.
+    /// Borrowed reference (not ref-counted) to avoid Generator↔Frame cycle.
+    /// Cleared by the generator's Drop impl.
+    pub generator: PyAtomicBorrow,
 }
 
 impl PyPayload for Frame {
@@ -114,7 +117,7 @@ unsafe impl Traverse for Frame {
         self.trace.traverse(tracer_fn);
         self.state.traverse(tracer_fn);
         self.temporary_refs.traverse(tracer_fn);
-        self.generator.traverse(tracer_fn);
+        // generator is a borrowed reference, not traversed
     }
 }
 
@@ -175,12 +178,19 @@ impl Frame {
             trace_lines: PyMutex::new(true),
             trace_opcodes: PyMutex::new(false),
             temporary_refs: PyMutex::new(vec![]),
-            generator: PyMutex::new(None),
+            generator: PyAtomicBorrow::new(),
         }
     }
 
-    pub fn set_generator(&self, generator: PyObjectRef) {
-        *self.generator.lock() = Some(generator);
+    /// Store a borrowed back-reference to the owning generator/coroutine.
+    /// The caller must ensure the generator outlives the frame.
+    pub fn set_generator(&self, generator: &PyObject) {
+        self.generator.store(generator);
+    }
+
+    /// Clear the generator back-reference. Called when the generator is finalized.
+    pub fn clear_generator(&self) {
+        self.generator.clear();
     }
 
     pub fn current_location(&self) -> SourceLocation {