"Generally, mixed-mode arithmetic combining real and complex variables should
be performed directly, not by first coercing the real to complex, lest the sign
of zero be rendered uninformative; the same goes for combinations of pure
imaginary quantities with complex variables." (c) Kahan, W: Branch cuts for
complex elementary functions.
This patch implements mixed-mode arithmetic rules, combining real and
complex variables as specified by C standards since C99 (in particular,
there is no special version for the true division with real lhs
operand). Most C compilers implementing C99+ Annex G have only these
special rules (without support for imaginary type, which is going to be
deprecated in C2y).
This adds authentication to the forkserver control socket. In the past only filesystem permissions protected this socket from code injection into the forkserver process by limiting access to the same UID, which didn't exist when Linux abstract namespace sockets were used (see issue) meaning that any process in the same system network namespace could inject code. We've since stopped using abstract namespace sockets by default, but protecting our control sockets regardless of type is a good idea.
This reuses the HMAC based shared key auth already used by `multiprocessing.connection` sockets for other purposes.
Doing this is useful so that filesystem permissions are not relied upon and trust isn't implied by default between all processes running as the same UID with access to the unix socket.
### pyperformance benchmarks
No significant changes. Including `concurrent_imap` which exercises `multiprocessing.Pool.imap` in that suite.
### Microbenchmarks
This does _slightly_ slow down forkserver use. How much so appears to depend on the platform. Modern platforms and simple platforms are less impacted. This PR adds additional IPC round trips to the control socket to tell forkserver to spawn a new process. Systems with potentially high latency IPC are naturally impacted more.
Typically a 1-4% slowdown on a very targeted process creation microbenchmark, with a worst case overloaded system slowdown of 20%. No evidence that these slowdowns appear in practical sense. See the PR for details.
If the cpXXX encoding is not directly implemented in Python, fall back
to use the Windows-specific API codecs.code_page_encode() and
codecs.code_page_decode().
Accepting objects with false values (like 0 and []) except empty strings
and byte-like objects and None in urllib.parse functions parse_qsl() and
parse_qs() is now deprecated.
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Replace the os.environ.refresh() method with a new
os.reload_environ() function.
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Add `pathlib.Path.scandir()` as a trivial wrapper of `os.scandir()`. This
will be used to implement several `PathBase` methods more efficiently,
including methods that provide `Path.copy()`.
They used to be shared, before 3.12. Returning to sharing them resolves a failure on Py_TRACE_REFS builds.
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Previously, copying a super object returned a copy of the instance
invoking super(). Pickling a super object could pickle the instance
invoking super() or fail, depending on its type and protocol.
Now deep copying returns a new super object and pickling pickles the super
object. Shallow copying returns the same super object.
This is an implementation of InterpreterPoolExecutor that builds on ThreadPoolExecutor.
(Note that this is not tied to PEP 734, which is strictly about adding a new stdlib module.)
Possible future improvements:
* support passing a script for the initializer or to submit()
* support passing (most) arbitrary functions without pickling
* support passing closures
* optionally exec functions against __main__ instead of the their original module
It is an alternate constructor which only accepts a single numeric argument.
Unlike to Decimal.from_float() it accepts also Decimal.
Unlike to the standard constructor, it does not accept strings and tuples.
It is an alternative constructor which only accepts a single numeric argument.
Unlike to Fraction.from_float() and Fraction.from_decimal() it accepts any
real numbers supported by the standard constructor (int, float, Decimal,
Rational numbers, objects with as_integer_ratio()).
Unlike to the standard constructor, it does not accept strings.
The function now sets temporarily the LC_CTYPE locale to the locale
of the category that determines the requested value if the locales are
different and the resulting string is non-ASCII.
This temporary change affects other threads.
It can now have one of three forms:
* basename(argv0) -- for simple scripts
* python arv0 -- for directories, ZIP files, etc
* python -m module -- for imported modules
Co-authored-by: Alyssa Coghlan <ncoghlan@gmail.com>
Change the default multiprocessing start method away from fork to forkserver or spawn on the remaining platforms where it was fork. See the issue for context. This makes the default far more thread safe (other than for people spawning threads at import time... - don't do that!).
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Sergey B Kirpichev
Victor Stinner
Savannah Ostrowski
Gregory P. Smith
Jun Komoda
Barney Gale
Hugo van Kemenade
Serhiy Storchaka
Seth Michael Larson
Bénédikt Tran
Peter Bierma
RUANG (James Roy)
Sayandip Dutta
Sahil Prajapati
Cody Maloney
Nice Zombies
Kumar Aditya
Brian Schubert
Zhikang Yan
Eric Snow
Jacob Walls
Jelle Zijlstra