diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py index c37f0e1387980c..7ecec9638489df 100644 --- a/Lib/asyncio/tasks.py +++ b/Lib/asyncio/tasks.py @@ -445,8 +445,13 @@ async def wait_for(fut, timeout, *, loop=None): if fut.done(): return fut.result() - fut.cancel() - raise exceptions.TimeoutError() + await _cancel_and_wait(fut, loop=loop) + try: + fut.result() + except exceptions.CancelledError as exc: + raise exceptions.TimeoutError() from exc + else: + raise exceptions.TimeoutError() waiter = loop.create_future() timeout_handle = loop.call_later(timeout, _release_waiter, waiter) diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py index f9db066ce89837..511961c32005a0 100644 --- a/Lib/test/test_asyncio/test_tasks.py +++ b/Lib/test/test_asyncio/test_tasks.py @@ -1131,6 +1131,9 @@ async def inner(): nonlocal task_done try: await asyncio.sleep(0.2) + except asyncio.CancelledError: + await asyncio.sleep(_EPSILON) + raise finally: task_done = True @@ -1145,6 +1148,34 @@ async def inner(): chained = cm.exception.__context__ self.assertEqual(type(chained), asyncio.CancelledError) + def test_wait_for_waits_for_task_cancellation_w_timeout_0(self): + loop = asyncio.new_event_loop() + self.addCleanup(loop.close) + + task_done = False + + async def foo(): + async def inner(): + nonlocal task_done + try: + await asyncio.sleep(10) + except asyncio.CancelledError: + await asyncio.sleep(_EPSILON) + raise + finally: + task_done = True + + inner_task = self.new_task(loop, inner()) + await asyncio.sleep(_EPSILON) + await asyncio.wait_for(inner_task, timeout=0) + + with self.assertRaises(asyncio.TimeoutError) as cm: + loop.run_until_complete(foo()) + + self.assertTrue(task_done) + chained = cm.exception.__context__ + self.assertEqual(type(chained), asyncio.CancelledError) + def test_wait_for_reraises_exception_during_cancellation(self): loop = asyncio.new_event_loop() self.addCleanup(loop.close) diff --git a/Misc/NEWS.d/next/Library/2020-08-15-15-50-12.bpo-32751.85je5X.rst b/Misc/NEWS.d/next/Library/2020-08-15-15-50-12.bpo-32751.85je5X.rst new file mode 100644 index 00000000000000..c172ce5d9e9487 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-08-15-15-50-12.bpo-32751.85je5X.rst @@ -0,0 +1,3 @@ +When cancelling the task due to a timeout, :meth:`asyncio.wait_for` will now +wait until the cancellation is complete also in the case when *timeout* is +<= 0, like it does with positive timeouts.