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| -rw-r--r-- | Doc/library/asyncio-task.rst | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst index abf1726..4716a3f 100644 --- a/Doc/library/asyncio-task.rst +++ b/Doc/library/asyncio-task.rst @@ -414,6 +414,53 @@ reported by :meth:`asyncio.Task.cancelling`. Improved handling of simultaneous internal and external cancellations and correct preservation of cancellation counts. +Terminating a Task Group +------------------------ + +While terminating a task group is not natively supported by the standard +library, termination can be achieved by adding an exception-raising task +to the task group and ignoring the raised exception: + +.. code-block:: python + + import asyncio + from asyncio import TaskGroup + + class TerminateTaskGroup(Exception): + """Exception raised to terminate a task group.""" + + async def force_terminate_task_group(): + """Used to force termination of a task group.""" + raise TerminateTaskGroup() + + async def job(task_id, sleep_time): + print(f'Task {task_id}: start') + await asyncio.sleep(sleep_time) + print(f'Task {task_id}: done') + + async def main(): + try: + async with TaskGroup() as group: + # spawn some tasks + group.create_task(job(1, 0.5)) + group.create_task(job(2, 1.5)) + # sleep for 1 second + await asyncio.sleep(1) + # add an exception-raising task to force the group to terminate + group.create_task(force_terminate_task_group()) + except* TerminateTaskGroup: + pass + + asyncio.run(main()) + +Expected output: + +.. code-block:: text + + Task 1: start + Task 2: start + Task 1: done + Sleeping ======== |