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gh-155575: Fix eager tasks inheriting the creator's exception state #155578

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gh-155575: Fix eager tasks inheriting the creator's exception state #155578

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26 changes: 26 additions & 0 deletions Lib/test/test_asyncio/test_eager_task_factory.py
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,28 @@ async def run():
self.run_coro(run())
captured_current_task = None

def test_exception_state_not_inherited(self):
# gh-155575: the eager first step must not see the creator's exception
async def bare():
raise

async def explicit():
raise ValueError

async def run():
try:
raise ConnectionError
except ConnectionError:
t1 = self.loop.create_task(bare())
t2 = self.loop.create_task(explicit())
with self.assertRaises(RuntimeError):
await t1
with self.assertRaises(ValueError) as cm:
await t2
self.assertIsNone(cm.exception.__context__)

self.run_coro(run())

def test_all_tasks_with_eager_completion(self):
captured_all_tasks = None

Expand Down Expand Up @@ -297,6 +319,10 @@ def tearDown(self):
asyncio.all_tasks = asyncio.tasks.all_tasks = self._all_tasks
return super().tearDown()

# gh-155575: Python Task implementation cannot clear the exception state
@unittest.expectedFailure
def test_exception_state_not_inherited(self):
super().test_exception_state_not_inherited()


@unittest.skipUnless(hasattr(tasks, '_CTask'),
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2026-08-11-19-04-30.gh-issue-155575.0cCarD.rst
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@@ -0,0 +1 @@
Fix :mod:`asyncio` eager tasks inheriting the creator's exception state.
5 changes: 5 additions & 0 deletions Modules/_asynciomodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3477,9 +3477,14 @@ task_eager_start(_PyThreadStateImpl *ts, asyncio_state *state, TaskObj *task)
int retval = 0;

PyObject *stepres;
// gh-155575: this step runs on the creators stack, hide its exception state
_PyErr_StackItem exc_state = { .exc_value = NULL, .previous_item = NULL };
_PyErr_StackItem *prev_exc_info = ts->base.exc_info;
ts->base.exc_info = &exc_state;
Py_BEGIN_CRITICAL_SECTION(task);
stepres = task_step_impl(state, task, NULL);
Py_END_CRITICAL_SECTION();
ts->base.exc_info = prev_exc_info;
if (stepres == NULL) {
PyObject *exc = PyErr_GetRaisedException();
_PyErr_ChainExceptions1(exc);
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