https://github.com/python/cpython/commit/f76c43066fadbda6a87e94a0774934f30f762f2f commit: f76c43066fadbda6a87e94a0774934f30f762f2f branch: 3.15 author: Miss Islington (bot) <[email protected]> committer: hugovk <[email protected]> date: 2026-09-28T18:59:28+03:00 summary:
[3.15] gh-157301: Fix asyncio event loop hanging on a failed eager task start (GH-157302) (#157785) Co-authored-by: Timofei Ivankov <[email protected]> files: A Misc/NEWS.d/next/Library/2026-09-11-14-14-51.gh-issue-157301.QxcE2r.rst M Lib/asyncio/tasks.py M Lib/test/test_asyncio/test_tasks.py M Modules/_asynciomodule.c diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py index bd6a03f530afd2e..bdc577319c2ecc2 100644 --- a/Lib/asyncio/tasks.py +++ b/Lib/asyncio/tasks.py @@ -103,11 +103,20 @@ def __init__(self, coro, *, loop=None, name=None, context=None, self._coro = coro if context is None: self._context = contextvars.copy_context() + elif not isinstance(context, contextvars.Context): + # gh-157301: the passed value must be a contextvars.Context + self._log_destroy_pending = False + raise TypeError('a contextvars.Context was expected, ' + f'got {type(context).__name__}') else: self._context = context if eager_start and self._loop.is_running(): - self.__eager_start() + try: + self.__eager_start() + except: + self._log_destroy_pending = False + raise else: self._loop.call_soon(self.__step, context=self._context) _py_register_task(self) diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py index 3cb4679e8955bfa..a2f80edeb1d739b 100644 --- a/Lib/test/test_asyncio/test_tasks.py +++ b/Lib/test/test_asyncio/test_tasks.py @@ -2630,6 +2630,68 @@ async def main(): finally: loop.close() + def test_context_not_a_context(self): + # gh-157301 + async def coro(): + pass + + loop = asyncio.new_event_loop() + c = coro() + try: + with self.assertRaises(TypeError): + self.new_task(loop, c, context='not a context') + finally: + c.close() + loop.close() + + def test_context_not_a_context_leaves_loop_usable(self): + # gh-157301 + async def coro(): + pass + + async def main(): + c = coro() + try: + with self.assertRaises(TypeError): + self.new_task(loop, c, context='not a context', + eager_start=True) + finally: + c.close() + await asyncio.sleep(0) + + loop = asyncio.new_event_loop() + loop.call_later(support.SHORT_TIMEOUT, loop.stop) + try: + loop.run_until_complete(self.new_task(loop, main())) + finally: + loop.close() + + def test_context_already_entered_leaves_loop_usable(self): + # gh-157301 + async def coro(): + pass + + async def main(): + ctx = contextvars.copy_context() + + def inside(): + c = coro() + try: + with self.assertRaises(RuntimeError): + self.new_task(loop, c, context=ctx, eager_start=True) + finally: + c.close() + + ctx.run(inside) + await asyncio.sleep(0) + + loop = asyncio.new_event_loop() + loop.call_later(support.SHORT_TIMEOUT, loop.stop) + try: + loop.run_until_complete(self.new_task(loop, main())) + finally: + loop.close() + def test_context_2(self): cvar = contextvars.ContextVar('cvar', default='nope') diff --git a/Misc/NEWS.d/next/Library/2026-09-11-14-14-51.gh-issue-157301.QxcE2r.rst b/Misc/NEWS.d/next/Library/2026-09-11-14-14-51.gh-issue-157301.QxcE2r.rst new file mode 100644 index 000000000000000..9a1d2e435be9066 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-09-11-14-14-51.gh-issue-157301.QxcE2r.rst @@ -0,0 +1,2 @@ +Fix :class:`asyncio.Task` hanging the event loop when an eager start fails +to enter the task's context. diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c index a27190dadcd48c0..ff7991827ee9635 100644 --- a/Modules/_asynciomodule.c +++ b/Modules/_asynciomodule.c @@ -2333,6 +2333,13 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop, if (self->task_context == NULL) { return -1; } + } else if (!PyContext_CheckExact(context)) { + // gh-157301: the passed value must be a contextvars.Context + self->task_log_destroy_pending = 0; + PyErr_Format(PyExc_TypeError, + "a contextvars.Context was expected, got %T", + context); + return -1; } else { Py_XSETREF(self->task_context, Py_NewRef(context)); } @@ -3478,7 +3485,13 @@ task_eager_start(_PyThreadStateImpl *ts, asyncio_state *state, TaskObj *task) // it will continue as a regular (non-eager) asyncio task register_task(ts, task); + assert(PyContext_CheckExact(task->task_context)); if (_PyContext_Enter(&ts->base, task->task_context) == -1) { + // gh-157301: a failed enter must not leave the task current and registered + task->task_log_destroy_pending = 0; + PyObject *curtask = swap_current_task(ts, task->task_loop, prevtask); + Py_XDECREF(curtask); + unregister_task(task); Py_DECREF(prevtask); return -1; } _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
