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gh-126083: Fix a reference leak in asyncio.Task when reinitializing with new non-None context#126103

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Merged
sobolevn merged 4 commits into from
Oct 31, 2024
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gh-126083: Fix a reference leak in asyncio.Task when reinitializing with new non-None context #126103

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614d20f
Fix ref leak and add tests
Nico-Posada Oct 29, 2024
8e5effe
Address review comments
Nico-Posada Oct 29, 2024
a588f7b
fix linter errors
Nico-Posada Oct 29, 2024
2e70b51
Address sobolevn's review
Nico-Posada Oct 30, 2024
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22 changes: 22 additions & 0 deletions Lib/test/test_asyncio/test_tasks.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -2688,6 +2688,28 @@ def test_get_context(self):
finally:
loop.close()

def test_proper_refcounts(self):
# see: https://github.com/python/cpython/issues/126083
class Break:
def __str__(self):
raise RuntimeError("break")

obj = object()
initial_refcount = sys.getrefcount(obj)

coro = coroutine_function()
loop = asyncio.new_event_loop()
task = asyncio.Task.__new__(asyncio.Task)

for _ in range(5):
with self.assertRaisesRegex(RuntimeError, 'break'):
task.__init__(coro, loop=loop, context=obj, name=Break())

coro.close()
del task

self.assertEqual(sys.getrefcount(obj), initial_refcount)
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@kumaraditya303kumaraditya303Nov 2, 2024•
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Please avoid tests for exact refcounts, the test should test that no references are leaked rather than reference count should be equal, both are not same thing. In this particular case all of this seems unnecessary, our existing refleak checker is sufficient for this.

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@Nico-PosadaNico-PosadaNov 2, 2024

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Oh I was unaware of the existing refleak checker. Do you have any examples of where it's used so i can check it out?

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@picnixzpicnixzNov 2, 2024

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You can run python -m test XXX -R : (it's with -R :)



def add_subclass_tests(cls):
BaseTask = cls.Task
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2024-10-28-22-35-22.gh-issue-126083.TuI--n.rst
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
Fixed a reference leak in :class:`asyncio.Task` objects when reinitializing the same object with a non-``None`` context. Patch by Nico Posada.
2 changes: 1 addition & 1 deletion Modules/_asynciomodule.c
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Expand Up@@ -2120,7 +2120,7 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop,
return -1;
}
} else{
self->task_context = Py_NewRef(context);
Py_XSETREF(self->task_context, Py_NewRef(context));
}

Py_CLEAR(self->task_fut_waiter);
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