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GeezerVison is showing github.com — gh-128307: support eager_start kwarg in create_eager_task_factory, and pass kwargs from asyncio.create_task and TaskGroup.create_task by graingert · Pull Request #128306 · python/cpython

gh-128307: support eager_start kwarg in create_eager_task_factory, and pass kwargs from asyncio.create_task and TaskGroup.create_task #128306

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Merged
gvanrossum merged 26 commits into python:main from graingert:add-eager-start-to-create-task
May 5, 2025

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gh-128307: support eager_start kwarg in create_eager_task_factory, and pass kwargs from asyncio.create_task and TaskGroup.create_task #128306

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23d2c42
support eager_start kwarg in create_eager_task_factory
graingert Dec 28, 2024
da5cab3
📜🤖 Added by blurb_it.
blurb-it[bot] Dec 28, 2024
7bce401
Update Misc/NEWS.d/next/Library/2024-12-28-11-01-36.gh-issue-128307.B…
graingert Dec 28, 2024
8ad26fc
Update Lib/asyncio/base_events.py
graingert Jan 21, 2025
90f9ef2
Update Lib/asyncio/tasks.py
graingert Jan 21, 2025
1107608
use presense rather than None-ness to determine default eager_start b…
graingert Jan 21, 2025
ec3bd14
Update Doc/library/asyncio-eventloop.rst
graingert Jan 21, 2025
939c3f5
Merge branch 'main' into add-eager-start-to-create-task
graingert Jan 21, 2025
d24d43b
Update Misc/NEWS.d/next/Library/2024-12-28-11-01-36.gh-issue-128307.B…
graingert Jan 21, 2025
d8369c3
Merge branch 'main' into add-eager-start-to-create-task
graingert Jan 26, 2025
4a4ad1b
Apply suggestions from code review
graingert Jan 26, 2025
813398c
Merge branch 'main' into add-eager-start-to-create-task
graingert Mar 25, 2025
dfafc7a
Merge branch 'main' into add-eager-start-to-create-task
graingert Mar 25, 2025
3175aae
use self.current_task
graingert Mar 25, 2025
0598877
Merge branch 'main' into add-eager-start-to-create-task
graingert Apr 10, 2025
3e8e2a8
Merge branch 'main' into add-eager-start-to-create-task
graingert Apr 19, 2025
1c10063
Merge branch 'main' into add-eager-start-to-create-task
graingert Apr 22, 2025
5288bf2
Merge branch 'main' into add-eager-start-to-create-task
graingert Apr 29, 2025
14e0536
Update Doc/library/asyncio-eventloop.rst
graingert May 4, 2025
73a20a5
Merge branch 'main' into add-eager-start-to-create-task
graingert May 4, 2025
c92e2fa
test eager start with default factory
graingert May 4, 2025
8aab5f1
Merge branch 'main' into add-eager-start-to-create-task
graingert May 5, 2025
a410125
Merge branch 'main' into add-eager-start-to-create-task
graingert May 5, 2025
1a45d43
Change TaskGroup.create_task and tasks.create_task to **kwargs
gvanrossum-ms May 5, 2025
7654a85
Fix bug I introduced in tasks.create_task()
gvanrossum-ms May 5, 2025
74b02d4
Update Lib/asyncio/tasks.py
graingert May 5, 2025
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10 changes: 9 additions & 1 deletion 10 Doc/library/asyncio-eventloop.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -361,7 +361,7 @@ Creating Futures and Tasks

.. versionadded:: 3.5.2

.. method:: loop.create_task(coro, *, name=None, context=None)
.. method:: loop.create_task(coro, *, name=None, context=None, eager_start=None)
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Schedule the execution of :ref:`coroutine <coroutine>` *coro*.
Return a :class:`Task` object.
Expand All @@ -377,12 +377,20 @@ Creating Futures and Tasks
custom :class:`contextvars.Context` for the *coro* to run in.
The current context copy is created when no *context* is provided.

An optional keyword-only *eager_start* argument allows specifying
if the task should execute eagerly during the call to create_task,
or be scheduled later. If *eager_start* is not passed the mode set
by :meth:`loop.set_task_factory` will be used.

.. versionchanged:: 3.8
Added the *name* parameter.

.. versionchanged:: 3.11
Added the *context* parameter.

.. versionchanged:: next
Added the *eager_start* parameter.

.. method:: loop.set_task_factory(factory)

Set a task factory that will be used by
Expand Down
2 changes: 1 addition & 1 deletion 2 Lib/asyncio/base_events.py
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Expand Up @@ -459,7 +459,7 @@ def create_future(self):
return futures.Future(loop=self)

def create_task(self, coro, **kwargs):
"""Schedule a coroutine object.
"""Schedule or begin executing a coroutine object.
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Return a task object.
"""
Expand Down
7 changes: 2 additions & 5 deletions 7 Lib/asyncio/taskgroups.py
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Expand Up @@ -179,7 +179,7 @@ async def _aexit(self, et, exc):
exc = None


def create_task(self, coro, *, name=None, context=None):
def create_task(self, coro, **kwargs):
"""Create a new task in this group and return it.

Similar to `asyncio.create_task`.
Expand All @@ -193,10 +193,7 @@ def create_task(self, coro, *, name=None, context=None):
if self._aborting:
coro.close()
raise RuntimeError(f"TaskGroup {self!r} is shutting down")
if context is None:
task = self._loop.create_task(coro, name=name)
else:
task = self._loop.create_task(coro, name=name, context=context)
task = self._loop.create_task(coro, **kwargs)

futures.future_add_to_awaited_by(task, self._parent_task)

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14 changes: 4 additions & 10 deletions 14 Lib/asyncio/tasks.py
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Expand Up @@ -386,19 +386,13 @@ def __wakeup(self, future):
Task = _CTask = _asyncio.Task


def create_task(coro, *, name=None, context=None):
def create_task(coro, **kwargs):
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@dimaqq dimaqq May 6, 2025

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From the Python user perspective, I don't like this change.
It obscures the allowed kwargs and makes it harder for IDEs to provide suggestions.

I suppose we'd be relying on https://github.com/python/typeshed/blob/main/stdlib/asyncio/tasks.pyi from now on?

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@gvanrossum gvanrossum May 6, 2025

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I agree it would be nice if we could avoid the **kwargs, but it make the implementation more complex at every level of indirection (asyncio.create_task -> loop.create_task -> Task, and also TaskGroup.create_task -> loop.create_task -> Task).

IDEs should be using typeshed anyway. (And we should update tasks.pyi to have a case for 3.14 that adds eager_start and **kwargs. In fact this should be done to all the create_task definitions found in typeshed's asyncio definitions.

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"""Schedule the execution of a coroutine object in a spawn task.
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Return a Task object.
"""
loop = events.get_running_loop()
if context is None:
# Use legacy API if context is not needed
task = loop.create_task(coro, name=name)
else:
task = loop.create_task(coro, name=name, context=context)

return task
return loop.create_task(coro, **kwargs)


# wait() and as_completed() similar to those in PEP 3148.
Expand Down Expand Up @@ -1030,9 +1024,9 @@ def create_eager_task_factory(custom_task_constructor):
used. E.g. `loop.set_task_factory(asyncio.eager_task_factory)`.
"""

def factory(loop, coro, *, name=None, context=None):
def factory(loop, coro, *, eager_start=True, **kwargs):
return custom_task_constructor(
coro, loop=loop, name=name, context=context, eager_start=True)
coro, loop=loop, eager_start=eager_start, **kwargs)

return factory

Expand Down
37 changes: 37 additions & 0 deletions 37 Lib/test/test_asyncio/test_eager_task_factory.py
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Expand Up @@ -263,6 +263,24 @@ async def run():

self.run_coro(run())

def test_eager_start_false(self):
name = None

async def asyncfn():
nonlocal name
name = asyncio.current_task().get_name()

async def main():
t = asyncio.get_running_loop().create_task(
asyncfn(), eager_start=False, name="example"
)
self.assertFalse(t.done())
self.assertIsNone(name)
await t
self.assertEqual(name, "example")

self.run_coro(main())


class PyEagerTaskFactoryLoopTests(EagerTaskFactoryLoopTests, test_utils.TestCase):
Task = tasks._PyTask
Expand Down Expand Up @@ -505,5 +523,24 @@ def tearDown(self):
asyncio.current_task = asyncio.tasks.current_task = self._current_task
return super().tearDown()


class DefaultTaskFactoryEagerStart(test_utils.TestCase):
def test_eager_start_true_with_default_factory(self):
name = None

async def asyncfn():
nonlocal name
name = asyncio.current_task().get_name()

async def main():
t = asyncio.get_running_loop().create_task(
asyncfn(), eager_start=True, name="example"
)
self.assertTrue(t.done())
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self.assertEqual(name, "example")
await t

asyncio.run(main(), loop_factory=asyncio.EventLoop)

if __name__ == '__main__':
unittest.main()
33 changes: 31 additions & 2 deletions 33 Lib/test/test_asyncio/test_tasks.py
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Expand Up @@ -89,8 +89,8 @@ class BaseTaskTests:
Future = None
all_tasks = None

def new_task(self, loop, coro, name='TestTask', context=None):
return self.__class__.Task(coro, loop=loop, name=name, context=context)
def new_task(self, loop, coro, name='TestTask', context=None, eager_start=None):
return self.__class__.Task(coro, loop=loop, name=name, context=context, eager_start=eager_start)

def new_future(self, loop):
return self.__class__.Future(loop=loop)
Expand Down Expand Up @@ -2686,6 +2686,35 @@ async def main():

self.assertEqual([None, 1, 2], ret)

def test_eager_start_true(self):
name = None

async def asyncfn():
nonlocal name
name = self.current_task().get_name()

async def main():
t = self.new_task(coro=asyncfn(), loop=asyncio.get_running_loop(), eager_start=True, name="example")
self.assertTrue(t.done())
self.assertEqual(name, "example")
await t

def test_eager_start_false(self):
name = None

async def asyncfn():
nonlocal name
name = self.current_task().get_name()

async def main():
t = self.new_task(coro=asyncfn(), loop=asyncio.get_running_loop(), eager_start=False, name="example")
self.assertFalse(t.done())
self.assertIsNone(name)
await t
self.assertEqual(name, "example")

asyncio.run(main(), loop_factory=asyncio.EventLoop)

def test_get_coro(self):
loop = asyncio.new_event_loop()
coro = coroutine_function()
Expand Down
1 change: 1 addition & 0 deletions 1 Misc/NEWS.d/next/Library/2024-12-28-11-01-36.gh-issue-128307.BRCYTA.rst
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@@ -0,0 +1 @@
Add ``eager_start`` keyword argument to :meth:`asyncio.loop.create_task`
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