Hood Chatham [Mon, 20 May 2024 17:42:15 +0000 (13:42 -0400)]
DOCS: Suggest always calling exec with a globals argument and no locals argument (GH-119235)
Many users think they want a locals argument for various reasons but they do not
understand that it makes code be treated as a class definition. They do not want
their code treated as a class definition and get surprised. The reason not
to pass locals specifically is that the following code raises a `NameError`:
```py
exec("""
def f():
print("hi")
f()
def g():
f()
g()
""", {}, {})
```
The reason not to leave out globals is as follows:
pulkin [Sun, 19 May 2024 21:46:37 +0000 (23:46 +0200)]
gh-119105: difflib: improve recursion for degenerate cases (#119131)
Code from https://github.com/pulkin, in PR
https://github.com/python/cpython/pull/119131
Greatly speeds `Differ` when there are many identically scoring pairs, by splitting the recursion near the inputs' midpoints instead of degenerating (as now) into just peeling off the first two lines.
Jelle Zijlstra [Sun, 19 May 2024 02:15:14 +0000 (22:15 -0400)]
marshal docs: Remove reference to "Sun" (#119161)
Nobody has been using a Sun machine for a long time. When I saw
this sentence in a lightning talk just now, I thought it was talking
about sending Python code on a spacecraft.
Tim Peters [Sun, 19 May 2024 01:54:23 +0000 (20:54 -0500)]
Try to repair oddball test bots timing out in test_int (#119166)
Various test bots (outside the ones GH normally runs) are timing out during test_int after ecd8664 (asymptotically faster str->int). Best guess is that they don't build the C _decimal module. So require that module in the most likely tests to time out then. Flying mostly blind, though!
Asymptotically faster (O(n log n)) str->int for very large strings, leveraging the faster multiplication scheme in the C-coded `_decimal` when available. This is used instead of the current Karatsuba-limited method starting at 2 million digits.
Lots of opportunity remains for fine-tuning. Good targets include changing BYTELIM, and possibly changing the internal output base (from 256 to a higher number of bytes).
Doing this was substantial work, and many of the new lines are actually comments giving correctness proofs. The obvious approaches sticking to integers were too slow to be useful, so this is doing variable-precision decimal floating-point arithmetic. Much faster, but worst-possible rounding errors have to be wholly accounted for, using as little precision as possible.
Special thanks to Serhiy Storchaka for asking many good questions in his code reviews!
Jelle Zijlstra [Wed, 15 May 2024 02:39:12 +0000 (22:39 -0400)]
3.13 What's New: Add PEP 702 (#118922)
I honestly forgot this slipped into 3.13, but I think it's worth highlighting more, as it is a PEP-sized change that makes the type system significantly more powerful.
@Yhg1s I think it's also worth mentioning in your release announcements.
Barney Gale [Tue, 14 May 2024 17:53:15 +0000 (18:53 +0100)]
GH-101357: Suppress `OSError` from `pathlib.Path.exists()` and `is_*()` (#118243)
Suppress all `OSError` exceptions from `pathlib.Path.exists()` and `is_*()`
rather than a selection of more common errors as we do presently. Also
adjust the implementations to call `os.path.exists()` etc, which are much
faster on Windows thanks to GH-101196.
Sam Gross [Fri, 10 May 2024 20:29:29 +0000 (16:29 -0400)]
gh-118846: Fix free-threading test failures when run sequentially (#118864)
The free-threaded build currently immortalizes some objects once the
first thread is started. This can lead to test failures depending on the
order in which tests are run. This PR addresses those failures by
suppressing immortalization or skipping the affected tests.
Victor Stinner [Fri, 10 May 2024 19:08:24 +0000 (21:08 +0200)]
gh-118702: Implement vectorcall for BaseException (#118703)
* BaseException_vectorcall() now creates a tuple from 'args' array.
* Creation an exception using BaseException_vectorcall() is now a
single function call, rather than having to call
BaseException_new() and then BaseException_init().
Calling BaseException_init() is inefficient since it overrides
the 'args' attribute.
* _PyErr_SetKeyError() now uses PyObject_CallOneArg() to create the
KeyError instance to use BaseException_vectorcall().
Jelle Zijlstra [Fri, 10 May 2024 16:55:49 +0000 (09:55 -0700)]
Rename typing._collect_parameters (#118900)
Unfortunately, released versions of typing_extensions
monkeypatch this function without the extra parameter, which makes
it so things break badly if current main is used with typing_extensions.
Fortunately, the monkeypatching is not needed on Python 3.13, because CPython
now implements PEP 696. By renaming the function, we prevent the monkeypatch
from breaking typing.py internals.
We keep the old name (raising a DeprecationWarning) to help other external users who call it.
Barney Gale [Fri, 10 May 2024 15:53:46 +0000 (16:53 +0100)]
GH-78707: Drop deprecated `pathlib.PurePath.[is_]relative_to()` arguments (#118780)
Remove support for supplying additional positional arguments to
`PurePath.relative_to()` and `is_relative_to()`. This has been deprecated
since Python 3.12.
Alex Turner [Fri, 10 May 2024 14:26:35 +0000 (15:26 +0100)]
gh-117657: Fix QSBR race condition (#118843)
`_Py_qsbr_unregister` is called when the PyThreadState is already
detached, so the access to `tstate->qsbr` isn't safe without locking the
shared mutex. Grab the `struct _qsbr_shared` from the interpreter
instead.
_PyWeakref_ClearRef was previously exposed in the public C-API, although
it begins with an underscore and is not documented. It's used by a few
C-API extensions. There is currently no alternative public API that can
replace its use.
_PyWeakref_ClearWeakRefsExceptCallbacks is the only thread-safe way to
use _PyWeakref_ClearRef in the free-threaded build. This exposes the C
symbol, but does not make the API public.
Victor Stinner [Fri, 10 May 2024 10:04:16 +0000 (12:04 +0200)]
gh-117873: Use positional-only parameters in _posixshmem (#118012)
* shm_unlink() parameter becomes positional-only.
* shm_open() first parameter (path) becomes positional-only,
the two following parameters remain positional-or-keyword.
Brett Simmers [Thu, 9 May 2024 21:02:39 +0000 (14:02 -0700)]
gh-117657: Replace TSAN suppresions with more specific rules (#118722)
Using `race:` filters out warnings if the function appears anywhere in
the stack trace. This can hide a lot of unrelated warnings, especially
for a function like `_PyEval_EvalFrameDefault`, which is somewhere on
the stack more often than not.
Change all free-threaded suppressions to `race_top:`, which only matches
the top frame, and add any new suppressions this exposes.
Sam Gross [Thu, 9 May 2024 20:03:45 +0000 (16:03 -0400)]
gh-116984: Make mimalloc header includes relative to the current file (#118808)
Some embedders and extensions include parts of the internal API. The
pycore_mimalloc.h file is transitively include by a number of other
internal headers. This avoids include errors for code that was
already including those headers.
Sam Gross [Thu, 9 May 2024 18:52:27 +0000 (14:52 -0400)]
gh-118561: Fix crash involving list.extend in free-threaded build (#118723)
The `list_preallocate_exact` function did not zero initialize array
contents. In the free-threaded build, this could expose uninitialized
memory to concurrent readers between the call to
`list_preallocate_exact` and the filling of the array contents with
items.