Example:
async with asyncio.timeout(5):
await some_task()
Will interrupt the await and raise TimeoutError if some_task() takes longer than 5 seconds.
Co-authored-by: Guido van Rossum <guido@python.org>
Also from the _asyncio C accelerator module,
and adjust one test that the change caused to fail.
For more discussion see the discussion starting here:
https://github.com/python/cpython/pull/31394#issuecomment-1053545331
(Basically, @asvetlov proposed to return False from cancel()
when there is already a pending cancellation, and I went along,
even though it wasn't necessary for the task group implementation,
and @agronholm has come up with a counterexample that fails
because of this change. So now I'm changing it back to the old
semantics (but still bumping the counter) until we can have a
proper discussion about this.)
This changes cancelling() and uncancel() to return the count of pending cancellations.
This can be used to avoid bugs in certain edge cases (e.g. two timeouts going off at the same time).
* Remove task group names (for now)
We're not sure that they are needed, and once in the code
we would never be able to get rid of them.
Yury wrote:
> Ideally, there should be a way for someone to build a "trace"
> of taskgroups/task leading to the current running task.
> We could do that using contextvars, but I'm not sure we should
> do that in 3.11.
* Pass optional name on to task in create_task()
* Remove a bunch of unused stuff
asyncio/taskgroups.py is an adaptation of taskgroup.py from EdgeDb, with the following key changes:
- Allow creating new tasks as long as the last task hasn't finished
- Raise [Base]ExceptionGroup (directly) rather than TaskGroupError deriving from MultiError
- Instead of monkey-patching the parent task's cancel() method,
add a new public API to Task
The Task class has a new internal flag, `_cancel_requested`, which is set when `.cancel()` is called successfully. The `.cancelling()` method returns the value of this flag. Further `.cancel()` calls while this flag is set return False. To reset this flag, call `.uncancel()`.
Thus, a Task that catches and ignores `CancelledError` should call `.uncancel()` if it wants to be cancellable again; until it does so, it is deemed to be busy with uninterruptible cleanup.
This new Task API helps solve the problem where TaskGroup needs to distinguish between whether the parent task being cancelled "from the outside" vs. "from inside".
Co-authored-by: Yury Selivanov <yury@edgedb.com>
Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>
This parameter was accidentally removed when fixing
https://bugs.python.org/issue45129, this reverts the unnecessary changes
there.
Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>
Due to significant security concerns, the reuse_address parameter of
asyncio.loop.create_datagram_endpoint, deprecated in Python 3.9, is
now removed. This is because of the behavior of the socket option
SO_REUSEADDR in UDP.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Remove the @asyncio.coroutine decorator
enabling legacy generator-based coroutines to be compatible with async/await
code; remove asyncio.coroutines.CoroWrapper used for wrapping
legacy coroutine objects in the debug mode.
The decorator has been deprecated
since Python 3.8 and the removal was initially scheduled for Python 3.10.
* [Enum] reduce scope of new format behavior
Instead of treating all Enums the same for format(), only user mixed-in
enums will be affected. In other words, IntEnum and IntFlag will not be
changing the format() behavior, due to the requirement that they be
drop-in replacements of existing integer constants.
If a user creates their own integer-based enum, then the new behavior
will apply:
class Grades(int, Enum):
A = 5
B = 4
C = 3
D = 2
F = 0
Now: format(Grades.B) -> DeprecationWarning and '4'
3.12: -> no warning, and 'B'
asyncio.get_event_loop() emits now a deprecation warning when it creates a new event loop.
In future releases it will became an alias of asyncio.get_running_loop().
Andrew Svetlov
Alex Grönholm
Stefan Zabka
Serhiy Storchaka
Guido van Rossum
Tin Tvrtković
Thomas Grainger
Nikita Sobolev
Alex Waygood
Kumar Aditya
Emiya
Jim Crist-Harif
Kumar Aditya
Sam Bull
Gregory P. Smith
Joongi Kim
Christian Clauss
Hugo van Kemenade
Jesús Cea
Mariusz Felisiak
Illia Volochii
Ethan Furman
Binbin
Pablo Galindo
Christian Heimes
Roberto Hueso
Richard Kojedzinszky