The main problem was that an unluckily timed task cancellation could cause
the semaphore to be stuck. There were also doubts about strict FIFO ordering
of tasks allowed to pass.
The Semaphore implementation was rewritten to be more similar to Lock.
Many tests for edge cases (including cancellation) were added.
This reverts commit 0587810698.
Reason: This broke buildbots (some warnings added by that commit are turned to errors in the SSL buildbot).
Repro: ./python Lib/test/ssltests.py
Warn on loop initialization, when setting the wakeup fd disturbs a previously set wakeup fd, and on loop closing, when upon resetting the wakeup fd, we find it has been changed by someone else.
When a task catches CancelledError and raises some other error,
the other error should not silently be suppressed.
Any scenario where a task crashes in cleanup upon cancellation
will now result in an ExceptionGroup wrapping the crash(es)
instead of propagating CancelledError and ignoring the side errors.
NOTE: This represents a change in behavior (hence the need to
change several tests). But it is only an edge case.
Co-authored-by: Thomas Grainger <tagrain@gmail.com>
Once the task group is shutting down, it should not be possible to create a new task.
Here "shutting down" means `self._aborting` is set, indicating that at least one task
has failed and we have cancelled all others.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Fix#91487
When transferring a small file, e.g. 256 KiB, the speed of this PR is comparable. However, if a large file, e.g. 65536 KiB, is transferred, asyncio UDP will be over 100 times faster than the original. The speed is presumably significantly faster if a larger file is transferred, e.g. 1048576 KiB.
Automerge-Triggered-By: GH:gpshead
The existing event loop `start_tls()` method is not sufficient for
connections using the streams API. The existing StreamReader works
because the new transport passes received data to the original protocol.
The StreamWriter must then write data to the new transport, and the
StreamReaderProtocol must be updated to close the new transport
correctly.
The new StreamWriter `start_tls()` updates itself and the reader
protocol to the new SSL transport.
Co-authored-by: Ian Good <icgood@gmail.com>
After a long deliberation we ended up feeling that the message argument for Future.cancel(), added in 3.9, was a bad idea, so we're deprecating it in 3.11 and plan to remove it in 3.13.
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().
test_unix_events.py no longer checks if waitstatus_to_exitcode() mock
has been called or not to make the test more functional, rather than
checking the exact implementation.
This is my first issue!
So, if there's anything wrong, please tell me!
Also, thank you always for all the contributors!
Automerge-Triggered-By: GH:asvetlov
* Update code after merge review from 1st1
* Use a sentinel approach for loop parameter
Remove unnecessary _get_running_loop patching
* Use more clear function name (_verify_parameter_is_marker -> _verify_no_loop)
* Add init method to _LoopBoundMixin to check that loop param wasn't used
# Improve asyncio.wait function
The original code creates the futures set two times.
We can create this set before, avoiding the second creation.
This new behaviour [breaks the aiokafka library](https://github.com/aio-libs/aiokafka/pull/672), because it gives an iterator to that function, so the second iteration become empty.
Automerge-Triggered-By: GH:1st1
Cyker Way
Kumar Aditya
Guido van Rossum
Michel Hidalgo
Hendrik Makait
Pamela Fox
Kirill
Yury Selivanov
Łukasz Langa
Thomas Grainger
Victor Stinner
Oleg Iarygin
David Hewitt
Alexander Shadchin
msoxzw
Andrew Svetlov
Vincent Bernat
Duprat
Maximilian Hils
Alex Grönholm
Stefan Zabka
Serhiy Storchaka
Tin Tvrtković
Nikita Sobolev
Alex Waygood
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
Chris Jerdonek
Zackery Spytz
Wansoo Kim
Yurii Karabas
Diogo Dutra