The default task name is "Task-<counter>" (if no name is passed in during Task creation).
This is initialized in `Task.__init__` (C impl) using string formatting, which can be quite slow.
Actually using the task name in real world code is not very common, so this is wasted init.
Let's defer this string formatting to the first time the name is read (in `get_name` impl),
so we don't need to pay the string formatting cost if the task name is never read.
We don't change the order in which tasks are assigned numbers (if they are) --
the number is set on task creation, as a PyLong instead of a formatted string.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
asyncio.get_event_loop() now always return either running event loop or
the result of get_event_loop_policy().get_event_loop() call. The latter
should now raise an RuntimeError if no current event loop was set
instead of creating and setting a new event loop.
It affects also a number of asyncio functions and constructors which
call get_event_loop() implicitly: ensure_future(), shield(), gather(),
etc.
DeprecationWarning is no longer emitted if there is no running event loop but
the current event loop was set.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
We do the following:
* move the generated _PyUnicode_InitStaticStrings() to its own file
* move the generated _PyStaticObjects_CheckRefcnt() to its own file
* include pycore_global_objects.h in extension modules instead of pycore_runtime_init.h
These changes help us avoid including things that aren't needed.
https://github.com/python/cpython/issues/90868
Replace "(PyCFunction)(void(*)(void))func" cast with
_PyCFunction_CAST(func).
Change generated by the command:
sed -i -e \
's!(PyCFunction)(void(\*)(void)) *\([A-Za-z0-9_]\+\)!_PyCFunction_CAST(\1)!g' \
$(find -name "*.c")
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.
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).
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>
We're no longer using _Py_IDENTIFIER() (or _Py_static_string()) in any core CPython code. It is still used in a number of non-builtin stdlib modules.
The replacement is: PyUnicodeObject (not pointer) fields under _PyRuntimeState, statically initialized as part of _PyRuntime. A new _Py_GET_GLOBAL_IDENTIFIER() macro facilitates lookup of the fields (along with _Py_GET_GLOBAL_STRING() for non-identifier strings).
https://bugs.python.org/issue46541#msg411799 explains the rationale for this change.
The core of the change is in:
* (new) Include/internal/pycore_global_strings.h - the declarations for the global strings, along with the macros
* Include/internal/pycore_runtime_init.h - added the static initializers for the global strings
* Include/internal/pycore_global_objects.h - where the struct in pycore_global_strings.h is hooked into _PyRuntimeState
* Tools/scripts/generate_global_objects.py - added generation of the global string declarations and static initializers
I've also added a --check flag to generate_global_objects.py (along with make check-global-objects) to check for unused global strings. That check is added to the PR CI config.
The remainder of this change updates the core code to use _Py_GET_GLOBAL_IDENTIFIER() instead of _Py_IDENTIFIER() and the related _Py*Id functions (likewise for _Py_GET_GLOBAL_STRING() instead of _Py_static_string()). This includes adding a few functions where there wasn't already an alternative to _Py*Id(), replacing the _Py_Identifier * parameter with PyObject *.
The following are not changed (yet):
* stop using _Py_IDENTIFIER() in the stdlib modules
* (maybe) get rid of _Py_IDENTIFIER(), etc. entirely -- this may not be doable as at least one package on PyPI using this (private) API
* (maybe) intern the strings during runtime init
https://bugs.python.org/issue46541
* Do not PUSH/POP traceback or type to the stack as part of exc_info
* Remove exc_traceback and exc_type from _PyErr_StackItem
* Add to what's new, because this change breaks things like Cython
setup.py no longer defines Py_BUILD_CORE_MODULE. Instead every
module defines the macro before #include "Python.h" unless
Py_BUILD_CORE_BUILTIN is already defined.
Py_BUILD_CORE_BUILTIN is defined for every module that is built by
Modules/Setup.
The PR also simplifies Modules/Setup. Makefile and makesetup
already define Py_BUILD_CORE_BUILTIN and include Modules/internal
for us.
Signed-off-by: Christian Heimes <christian@python.org>
Redefining the PyThreadState_GET() macro in pycore_pystate.h is
useless since it doesn't affect files not including it. Either use
_PyThreadState_GET() directly, or don't use pycore_pystate.h internal
C API. For example, the _testcapi extension don't use the internal C
API, but use the public PyThreadState_Get() function instead.
Replace PyThreadState_Get() with _PyThreadState_GET(). The
_PyThreadState_GET() macro is more efficient than PyThreadState_Get()
and PyThreadState_GET() function calls which call fail with a fatal
Python error.
posixmodule.c and _ctypes extension now include <windows.h> before
pycore header files (like pycore_call.h).
_PyTraceback_Add() now uses _PyErr_Fetch()/_PyErr_Restore() instead
of PyErr_Fetch()/PyErr_Restore().
The _decimal and _xxsubinterpreters extensions are now built with the
Py_BUILD_CORE_MODULE macro defined to get access to the internal C
API.
* Remove code that checks Py_TPFLAGS_HAVE_VERSION_TAG
The field is always present in the type struct, as explained
in the added comment.
* Remove Py_TPFLAGS_HAVE_AM_SEND
The flag is not needed, and since it was added in 3.10 it can be removed now.
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().
The new API allows to efficiently send values into native generators
and coroutines avoiding use of StopIteration exceptions to signal
returns.
ceval loop now uses this method instead of the old "private"
_PyGen_Send C API. This translates to 1.6x increased performance
of 'await' calls in micro-benchmarks.
Aside from CPython core improvements, this new API will also allow
Cython to generate more efficient code, benefiting high-performance
IO libraries like uvloop.
The running loop holder cache variable was always set to NULL when
calling set_running_loop.
Now set_running_loop saves the newly created running loop holder in the
cache variable for faster access in get_running_loop.
Automerge-Triggered-By: @1st1
This updates _PyErr_ChainStackItem() to use _PyErr_SetObject()
instead of _PyErr_ChainExceptions(). This prevents a hang in
certain circumstances because _PyErr_SetObject() performs checks
to prevent cycles in the exception context chain while
_PyErr_ChainExceptions() doesn't.
When an asyncio.Task is cancelled, the exception traceback now
starts with where the task was first interrupted. Previously,
the traceback only had "depth one."
Update _asyncio, _bz2, _csv, _curses, _datetime,
_io, _operator, _pickle, _queue, blake2,
multibytecodec and overlapped C extension modules
to use PyModule_AddType().
The bulk of this patch was generated automatically with:
for name in \
PyObject_Vectorcall \
Py_TPFLAGS_HAVE_VECTORCALL \
PyObject_VectorcallMethod \
PyVectorcall_Function \
PyObject_CallOneArg \
PyObject_CallMethodNoArgs \
PyObject_CallMethodOneArg \
;
do
echo $name
git grep -lwz _$name | xargs -0 sed -i "s/\b_$name\b/$name/g"
done
old=_PyObject_FastCallDict
new=PyObject_VectorcallDict
git grep -lwz $old | xargs -0 sed -i "s/\b$old\b/$new/g"
and then cleaned up:
- Revert changes to in docs & news
- Revert changes to backcompat defines in headers
- Nudge misaligned comments
bpo-38248, bpo-38321: Fix warning:
modules\_asynciomodule.c(2667):
warning C4102: 'set_exception': unreferenced label
The related goto has been removed by
commit edad4d89e3.
Add a new public PyObject_CallNoArgs() function to the C API: call a
callable Python object without any arguments.
It is the most efficient way to call a callback without any argument.
On x86-64, for example, PyObject_CallFunctionObjArgs(func, NULL)
allocates 960 bytes on the stack per call, whereas
PyObject_CallNoArgs(func) only allocates 624 bytes per call.
It is excluded from stable ABI 3.8.
Replace private _PyObject_CallNoArg() with public
PyObject_CallNoArgs() in C extensions: _asyncio, _datetime,
_elementtree, _pickle, _tkinter and readline.
It is now allowed to add new fields at the end of the PyTypeObject struct without having to allocate a dedicated compatibility flag in tp_flags.
This will reduce the risk of running out of bits in the 32-bit tp_flags value.
This will address the common mistake many asyncio users make:
an "except Exception" clause breaking Tasks cancellation.
In addition to this change, we stop inheriting asyncio.TimeoutError
and asyncio.InvalidStateError from their concurrent.futures.*
counterparts. There's no point for these exceptions to share the
inheritance chain.
In 3.9 we'll focus on implementing supervisors and cancel scopes,
which should allow better handling of all exceptions, including
SystemExit and KeyboardInterrupt
The C implementation of asyncio.Task currently fails to perform the
cancellation cleanup correctly in the following scenario.
async def task1():
async def task2():
await task3 # task3 is never cancelled
asyncio.current_task().cancel()
await asyncio.create_task(task2())
The actuall error is a hardcoded call to `future_cancel()` instead of
calling the `cancel()` method of a future-like object.
Thanks to Vladimir Matveev for noticing the code discrepancy and to
Yury Selivanov for coming up with a pathological scenario.
Fix the following bugs in the C implementation:
* get_future_loop() silenced all exceptions raised when look up the get_loop
attribute, not just an AttributeError.
* enter_task() silenced all exceptions raised when look up the current task,
not just a KeyError.
* repr() was called for a borrowed link in enter_task() and task_step_impl().
* str() was used instead of repr() in formatting one error message (in
Python implementation too).
* There where few reference leaks in error cases.
Specifically, it's not possible to subclass Task/Future classes
and override the following methods:
* Future._schedule_callbacks
* Task._step
* Task._wakeup
Itamar Ostricher
Kumar Aditya
Irit Katriel
Erlend E. Aasland
Shantanu
Serhiy Storchaka
Victor Stinner
Eric Snow
Guido van Rossum
Ofey Chan
Yury Selivanov
Łukasz Langa
Mark Shannon
Andrew Svetlov
Tin Tvrtković
Erlend Egeberg Aasland
Christian Heimes
Matthias Reichl
Petr Viktorin
Vladimir Matveev
Tony Solomonik
Rémi Lapeyre
Zackery Spytz
Chris Jerdonek
Jeffrey Quesnelle
Dong-hee Na
Andy Lester
Batuhan Taşkaya
Brandt Bucher
Ben Harper
Victor Stinner
Jeroen Demeyer
Alex Grönholm
Antoine Pitrou
Yury Selivanov
Inada Naoki
Elvis Pranskevichus
Benjamin Peterson
Oren Milman
Leo Arias