Mailman 3 February 2020 - Python-Dev

Hang with parallel make
by e2lahav＠gmail.com 29 Feb '20

29 Feb '20

Hello, I have successfully built Python 3.8.1 on QNX, but ran into a problem when using 'make -j4'. The build process invariably hangs with multiple single-threaded child processes stuck indefinitely waiting on semaphores. These semaphores will clearly never be posted to, as the processes are all single threaded and the semaphores are not shared with any other process. A backtrace shows that the the offending calls come from run_at_forkers(), which is not surprising. I consider a multi-threaded fork() to be an ill-defined operation and my arch-nemesis... The problem here is that the value of the semaphore inherited from the parent shows the semaphore to be unavailable, even though the semaphore *object* itself is not the same as the one used by the parent (they share the same virtual address, but in different address spaces with different backing memory). A few (noob) questions: 1. Is there a way to correlate the C backtrace from the core dump to the Python code that resulted in this hang? 2. It is well-known that a multi-threaded fork() is inherently unsafe, and POSIX says that no non-async-signal-safe operations are allowed between the fork() and exec() calls. I even saw comments to this effect in the Python source code ;-) So why is it done? 3. Any reason not to use posix_spawn() instead of fork()/exec()? While some systems implement posix_spawn() with fork()/exec() others (at least QNX) implements it without first creating a duplicate of the parent, making it both more efficient and safer in a multi-threaded parent. 4. thread_pthread.h seems to go to great lengths to implement locks without using native mutexes. I found one reference in the code dating to 1994 as to why that is done. Is it still applicable? Contrary to the claim in that comment the semantics for trying to lock an already-locked mutex and for unlocking an unowned mutex are well-defined. Thanks, --Elad

5 12

Summary of Python tracker Issues
by Python tracker 28 Feb '20

28 Feb '20

ACTIVITY SUMMARY (2020-02-21 - 2020-02-28) Python tracker at https://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 7333 (+18) closed 44202 (+52) total 51535 (+70) Open issues with patches: 2882 Issues opened (53) ================== #17422: language reference should specify restrictions on class namesp https://bugs.python.org/issue17422 reopened by eric.snow #25960: Popen.wait() hangs when called from a signal handler when os.w https://bugs.python.org/issue25960 reopened by gregory.p.smith #39715: Implement __repr__ methods for AST classes https://bugs.python.org/issue39715 opened by cool-RR #39716: argparse.ArgumentParser does not raise on duplicated subparser https://bugs.python.org/issue39716 opened by Antony.Lee #39717: Fix exception causes in tarfile module https://bugs.python.org/issue39717 opened by cool-RR #39718: TYPE_IGNORE, COLONEQUAL missing from py38 changes in token doc https://bugs.python.org/issue39718 opened by hauntsaninja #39719: tempfile.SpooledTemporaryFile still has softspace property https://bugs.python.org/issue39719 opened by hauntsaninja #39720: Signature.bind TypeErrors could be more helpful https://bugs.python.org/issue39720 opened by RazerM #39724: IDLE threading + stdout/stdin observed blocking behavior https://bugs.python.org/issue39724 opened by John Smith #39725: unrelated `from None` exceptions lose prior exception informa https://bugs.python.org/issue39725 opened by ethan.furman #39727: cgi.parse() fatally attempts str.decode when handling multipar https://bugs.python.org/issue39727 opened by James Edington #39728: Instantiating enum with invalid value results in ValueError tw https://bugs.python.org/issue39728 opened by jonasmalaco #39729: stat.S_ISXXX can raise OverflowError for remote file modes https://bugs.python.org/issue39729 opened by wiggin15 #39731: ModuleNotFoundError: No module named '_ctypes' https://bugs.python.org/issue39731 opened by alhelal #39732: plistlib should export UIDs in XML like Apple does https://bugs.python.org/issue39732 opened by Artoria2e5 #39734: Deprecate readinto() fallback path in _pickle.c https://bugs.python.org/issue39734 opened by pitrou #39735: Signal handler is invoked recursively https://bugs.python.org/issue39735 opened by msakai #39740: Select module fails to build on Solaris 11.4 https://bugs.python.org/issue39740 opened by RobHammann #39741: Argument Clinic name conflict https://bugs.python.org/issue39741 opened by BTaskaya #39742: Enhancement: add `os.getdtablesize(..)` to `os` (`posix`) modu https://bugs.python.org/issue39742 opened by ngie #39744: asyncio.subprocess's communicate(None) does not close stdin https://bugs.python.org/issue39744 opened by marmarek #39745: BlockingIOError.characters_written represents number of bytes https://bugs.python.org/issue39745 opened by msakai #39747: test_os debug assertion failure https://bugs.python.org/issue39747 opened by Ethan Smith #39750: UnicodeError becomes unpicklable if data is appended to args https://bugs.python.org/issue39750 opened by João Eiras #39751: multiprocessing breaks when payload fails to unpickle https://bugs.python.org/issue39751 opened by João Eiras #39752: multiprocessing halts when child process crashes/quits https://bugs.python.org/issue39752 opened by João Eiras #39753: inspecting a partial with bound keywods gives incorrect signat https://bugs.python.org/issue39753 opened by cjw296 #39756: Event sequence "KeyRelease-Shift_R" not being fired https://bugs.python.org/issue39756 opened by Devin Morgan #39758: StreamWriter.wait_closed() can hang indefinitely. https://bugs.python.org/issue39758 opened by tomchristie #39759: os.getenv documentation is misleading https://bugs.python.org/issue39759 opened by remi.lapeyre #39760: ast.FormattedValue.format_spec unnecessarily wrapped in Joined https://bugs.python.org/issue39760 opened by Ilya Kamenshchikov #39761: Python 3.9.0a4 fails to build when configured with --with-dtra https://bugs.python.org/issue39761 opened by Dormouse759 #39763: distutils.spawn should use subprocess (hang in parallel builds https://bugs.python.org/issue39763 opened by Elad Lahav #39764: PyAsyncGenObject causes task.get_stack() raising AttributeErro https://bugs.python.org/issue39764 opened by lidiz #39765: asyncio loop.add_signal_handler() may not behave as expected https://bugs.python.org/issue39765 opened by rogerdahl #39766: unittest's assertRaises removes locals from tracebacks https://bugs.python.org/issue39766 opened by blueyed #39767: create multiprocessing.SharedMemory by pointing to existing me https://bugs.python.org/issue39767 opened by Dariusz Trawinski #39768: remove tempfile.mktemp() https://bugs.python.org/issue39768 opened by wyz23x2 #39769: compileall.compile_dir(..., ddir="<prefix>") omits the interme https://bugs.python.org/issue39769 opened by gregory.p.smith #39770: Remove unnecessary size calculation in array_modexec in Module https://bugs.python.org/issue39770 opened by petdance #39771: EmailMessage.add_header doesn't work https://bugs.python.org/issue39771 opened by hwgdb Smith #39772: Python 2 FAQ shown in help(a)python.org auto reply https://bugs.python.org/issue39772 opened by wyz23x2 #39773: Export symbols for vectorcall https://bugs.python.org/issue39773 opened by David Hewitt #39774: Missing documentation on how to make package executable as scr https://bugs.python.org/issue39774 opened by igo95862 #39775: inspect.Signature.parameters should be an OrderedDict, not a p https://bugs.python.org/issue39775 opened by Antony.Lee #39776: Crash in decimal module in heavy-multithreaded scenario https://bugs.python.org/issue39776 opened by boytsovea #39777: Use the codecov GH Action https://bugs.python.org/issue39777 opened by brett.cannon #39778: collections.OrderedDict and weakref.ref raises "refcount is to https://bugs.python.org/issue39778 opened by leezu #39780: Add HTTP Response code 103 https://bugs.python.org/issue39780 opened by Ali McMaster #39781: IDLE: Do not jump when select in codecontext https://bugs.python.org/issue39781 opened by terry.reedy #39782: local varible referenced a Exception won't be collected in fun https://bugs.python.org/issue39782 opened by wangjie #39783: Optimize construction of Path from other Paths by just returni https://bugs.python.org/issue39783 opened by Antony.Lee #39784: Tuple comprehension https://bugs.python.org/issue39784 opened by Marco Sulla Most recent 15 issues with no replies (15) ========================================== #39784: Tuple comprehension https://bugs.python.org/issue39784 #39782: local varible referenced a Exception won't be collected in fun https://bugs.python.org/issue39782 #39781: IDLE: Do not jump when select in codecontext https://bugs.python.org/issue39781 #39773: Export symbols for vectorcall https://bugs.python.org/issue39773 #39772: Python 2 FAQ shown in help(a)python.org auto reply https://bugs.python.org/issue39772 #39770: Remove unnecessary size calculation in array_modexec in Module https://bugs.python.org/issue39770 #39767: create multiprocessing.SharedMemory by pointing to existing me https://bugs.python.org/issue39767 #39764: PyAsyncGenObject causes task.get_stack() raising AttributeErro https://bugs.python.org/issue39764 #39756: Event sequence "KeyRelease-Shift_R" not being fired https://bugs.python.org/issue39756 #39752: multiprocessing halts when child process crashes/quits https://bugs.python.org/issue39752 #39751: multiprocessing breaks when payload fails to unpickle https://bugs.python.org/issue39751 #39745: BlockingIOError.characters_written represents number of bytes https://bugs.python.org/issue39745 #39742: Enhancement: add `os.getdtablesize(..)` to `os` (`posix`) modu https://bugs.python.org/issue39742 #39740: Select module fails to build on Solaris 11.4 https://bugs.python.org/issue39740 #39735: Signal handler is invoked recursively https://bugs.python.org/issue39735 Most recent 15 issues waiting for review (15) ============================================= #39781: IDLE: Do not jump when select in codecontext https://bugs.python.org/issue39781 #39780: Add HTTP Response code 103 https://bugs.python.org/issue39780 #39775: inspect.Signature.parameters should be an OrderedDict, not a p https://bugs.python.org/issue39775 #39774: Missing documentation on how to make package executable as scr https://bugs.python.org/issue39774 #39770: Remove unnecessary size calculation in array_modexec in Module https://bugs.python.org/issue39770 #39769: compileall.compile_dir(..., ddir="<prefix>") omits the interme https://bugs.python.org/issue39769 #39765: asyncio loop.add_signal_handler() may not behave as expected https://bugs.python.org/issue39765 #39761: Python 3.9.0a4 fails to build when configured with --with-dtra https://bugs.python.org/issue39761 #39759: os.getenv documentation is misleading https://bugs.python.org/issue39759 #39744: asyncio.subprocess's communicate(None) does not close stdin https://bugs.python.org/issue39744 #39732: plistlib should export UIDs in XML like Apple does https://bugs.python.org/issue39732 #39728: Instantiating enum with invalid value results in ValueError tw https://bugs.python.org/issue39728 #39725: unrelated `from None` exceptions lose prior exception informa https://bugs.python.org/issue39725 #39719: tempfile.SpooledTemporaryFile still has softspace property https://bugs.python.org/issue39719 #39718: TYPE_IGNORE, COLONEQUAL missing from py38 changes in token doc https://bugs.python.org/issue39718 Top 10 most discussed issues (10) ================================= #36144: Dictionary union. (PEP 584) https://bugs.python.org/issue36144 29 msgs #39776: Crash in decimal module in heavy-multithreaded scenario https://bugs.python.org/issue39776 13 msgs #39717: Fix exception causes in tarfile module https://bugs.python.org/issue39717 12 msgs #39768: remove tempfile.mktemp() https://bugs.python.org/issue39768 12 msgs #39761: Python 3.9.0a4 fails to build when configured with --with-dtra https://bugs.python.org/issue39761 11 msgs #39763: distutils.spawn should use subprocess (hang in parallel builds https://bugs.python.org/issue39763 11 msgs #39771: EmailMessage.add_header doesn't work https://bugs.python.org/issue39771 10 msgs #39672: SIGSEGV crash on shutdown with shelve & c pickle https://bugs.python.org/issue39672 9 msgs #38597: C Extension import limit https://bugs.python.org/issue38597 8 msgs #39724: IDLE threading + stdout/stdin observed blocking behavior https://bugs.python.org/issue39724 8 msgs Issues closed (51) ================== #8269: Missing return values for PyUnicode C/API functions https://bugs.python.org/issue8269 closed by serhiy.storchaka #15474: Differentiate decorator and decorator factory in docs https://bugs.python.org/issue15474 closed by rhettinger #22947: Enable 'imageop' - "Multimedia Srvices Feature module" for 64- https://bugs.python.org/issue22947 closed by serhiy.storchaka #23080: BoundArguments.arguments should be unordered https://bugs.python.org/issue23080 closed by Antony.Lee #23164: "pydoc filter" documentation restrictive https://bugs.python.org/issue23164 closed by serhiy.storchaka #25397: improve ac_cv_have_long_long_format GCC fallback https://bugs.python.org/issue25397 closed by serhiy.storchaka #30566: punycode codec raises IndexError in decode_generalized_number( https://bugs.python.org/issue30566 closed by berker.peksag #31015: PyErr_WriteUnraisable should be more verbose in Python 2.7 https://bugs.python.org/issue31015 closed by serhiy.storchaka #34788: ipaddress module fails on rfc4007 scoped IPv6 addresses https://bugs.python.org/issue34788 closed by asvetlov #36000: __debug__ is a keyword but not a keyword https://bugs.python.org/issue36000 closed by cheryl.sabella #37539: CheckCommitCursorReset regression sqlite3 test fails with old https://bugs.python.org/issue37539 closed by berker.peksag #38101: Update devguide triaging keywords https://bugs.python.org/issue38101 closed by taleinat #38403: nuspec iconUrl field is deprecated https://bugs.python.org/issue38403 closed by steve.dower #38519: Internal include files missing on Windows https://bugs.python.org/issue38519 closed by steve.dower #38988: Killing asyncio subprocesses on timeout? https://bugs.python.org/issue38988 closed by asvetlov #39128: Document happy eyeball parameters in loop.create_connection si https://bugs.python.org/issue39128 closed by asvetlov #39130: Dict is reversable from v3.8 and should say that in the doc https://bugs.python.org/issue39130 closed by khalidmammadov #39139: Reference to depricated collections.abc class in collections i https://bugs.python.org/issue39139 closed by khalidmammadov #39180: Missing getlines func documentation from linecache module https://bugs.python.org/issue39180 closed by khalidmammadov #39382: abstract_issubclass() doesn't take bases tuple item ref https://bugs.python.org/issue39382 closed by serhiy.storchaka #39427: python -X options are not documented in the CLI --help https://bugs.python.org/issue39427 closed by pablogsal #39576: Surprising MemoryError in `decimal` with MAX_PREC https://bugs.python.org/issue39576 closed by tim.peters #39609: Set the thread_name_prefix for asyncio's default executor Thre https://bugs.python.org/issue39609 closed by asvetlov #39613: IsolatedAsyncioTestCase closes default event loop https://bugs.python.org/issue39613 closed by asvetlov #39636: Can't change Treeview row color in Tkinter https://bugs.python.org/issue39636 closed by terry.reedy #39642: Behaviour of disabled widgets: widget.bind(func) -vs- w = https://bugs.python.org/issue39642 closed by terry.reedy #39648: Expand math.gcd() and math.lcm() to accept multiple arguments https://bugs.python.org/issue39648 closed by mark.dickinson #39649: bdb.Bdb.format_stack_entry: checks for obsolete __args__ https://bugs.python.org/issue39649 closed by gvanrossum #39654: pyclbr: remove old references to class browser & add explain r https://bugs.python.org/issue39654 closed by terry.reedy #39657: Bezout and Chinese Remainder Theorem in the Standard Library? https://bugs.python.org/issue39657 closed by tim.peters #39681: pickle.load expects an object that implements readinto https://bugs.python.org/issue39681 closed by pitrou #39707: Abstract property setter/deleter implementation not enforced. https://bugs.python.org/issue39707 closed by gvanrossum #39721: Fix constness of members of tok_state struct. https://bugs.python.org/issue39721 closed by benjamin.peterson #39722: decimal differs between pure Python and C implementations https://bugs.python.org/issue39722 closed by rhettinger #39723: io.open_code should accept PathLike objects https://bugs.python.org/issue39723 closed by steve.dower #39726: ctypes on pypi has fallen behind https://bugs.python.org/issue39726 closed by David Harding #39730: Licence (license) for Python 3.8.1 is missing https://bugs.python.org/issue39730 closed by brett.cannon #39733: Bug in hypergeometric function https://bugs.python.org/issue39733 closed by SilentGhost #39736: const strings in Modules/_datetimemodule.c and Modules/_testbu https://bugs.python.org/issue39736 closed by benjamin.peterson #39737: Speed up list.__eq__ by about 6% https://bugs.python.org/issue39737 closed by serhiy.storchaka #39738: mod operation with large number is not correct. https://bugs.python.org/issue39738 closed by steven.daprano #39739: Python crash every time opening pycharm, seems related to tens https://bugs.python.org/issue39739 closed by mark.dickinson #39743: variable quiet is not defined in function main. https://bugs.python.org/issue39743 closed by SilentGhost #39746: Inappropriate short circuit relating to inequality comparison https://bugs.python.org/issue39746 closed by Orion Fisher #39748: PyScripter could not find Python 3.8 64 bits https://bugs.python.org/issue39748 closed by eric.smith #39749: python 3.8.1 (3.14 * 10 = 31.400000002 bug) https://bugs.python.org/issue39749 closed by steven.daprano #39754: update_one_slot() does not inherit sq_contains and mp_subscrip https://bugs.python.org/issue39754 closed by Marco Sulla #39755: Change example of itertools.product https://bugs.python.org/issue39755 closed by rhettinger #39757: EmailMessage wrong encoding for international domain https://bugs.python.org/issue39757 closed by Julien Castiaux #39762: PyLong_AS_LONG missing from longobject.h https://bugs.python.org/issue39762 closed by serhiy.storchaka #39779: [argparse] Add parameter to sort help output arguments https://bugs.python.org/issue39779 closed by rhettinger

1 0

Merging PRs without CLA signed
by Kyle Stanley 27 Feb '20

27 Feb '20

In a recently opened typo fixing PR [1], an issue came up regarding the lack of a signed CLA, where the author specifically mentioned they did not want to sign it for privacy concerns. In the past, I've seen several PRs with similarly minimal [2] changes (such as typo fixes, grammar fixes, link fixes, etc) merged without having the CLA signed, so it was my assumption that this was acceptable. For a full list of merged PRs to CPython with a "CLA not signed" label, see the following: https://github.com/python/cpython/pulls?utf8=%E2%9C%93&q=is%3Apr+state%3Ame… However, I was informed by Pablo Galindo that there are legal issues involved with merging *any* PRs without the CLA signed, including typo fixes. Personally, I have no strong opinion one way or the other, as I don't have an adequate understanding from a legal/licensing perspective. But, I think think there's definitely an issue with the lack of consistency regarding this policy. *To require a signed CLA for some minimal PRs but not others, solely based on who happens to be reviewing the PR, seems rather unfair to potential contributors.* From my perspective, the solution seems to be clearly defining a more explicit stance on this policy, and having it apply as universally as possible to *all* PRs made to CPython. For example, if the CLA should be required for all PRs, the policy might state something like this: "The author of any PR made to the CPython repository must have signed the CLA before their PR can be merged. Any PR opened by an author that has not signed the CLA can't be merged until it has been signed." OTOH, if it's okay for minimal PRs to not have a signed CLA: "The author of any PR made to the CPython repository must have signed the CLA before their PR can be merged, except for minimal PRs. Some examples of minimal PRs include: ..." Currently, the policy seems to be learning more towards the former based on the devguide [3], where it states "To accept your change we must have your formal approval for distributing your work under the PSF license. Therefore, you need to sign a contributor agreement which allows the Python Software Foundation to license your code for use with Python (you retain the copyright)". However, it seems apparent to me that either this policy isn't explicit enough, has a lack of visibility, or simply isn't followed consistently. What might be a viable solution to this problem? --- [1] - https://github.com/python/cpython/pull/18603 [2] - The term "minimal" can be interchanged with "trivial" for the most part in the above context, but I tend to prefer the former. IMO, it comes across as more respectful to the efforts made by the author, as even the smallest of PRs can require substantial efforts from first-time contributors that are entirely unfamiliar with the workflow; regardless of how small the change is. [3] - https://devguide.python.org/pullrequest/#licensing Regards, Kyle Stanley

11 16

Accepting PEP 584: Add Union Operators To dict
by Guido van Rossum 27 Feb '20

27 Feb '20

Now that the last bits of discussion about PEP 584 have been settled (we will *not* be calling the `copy` or `update` methods) I am accepting this PEP. Congratulations Steven and Brandt! Thanks to everyone else who gave their opinion. Formally, I will just send my recommendation to accept the PEP to the Steering Council -- they will then let us know whether they agree, and once that's done we can update the PEP with the "Accepted" status and land the implementation (https://github.com/python/cpython/pull/12088). (Hm, the PEP should probably also link to that PR rather than to Brandt's private branch.) -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-…>

10 27

Unpacking native bools in the struct module: Is Python relying on undefined behavior?
by Charalampos Stratakis 27 Feb '20

27 Feb '20

Hello folks, I recently observed a failure on the s390x fedora rawhide buildbot, on the clang builds, when clang got updated to version 10: https://bugs.python.org/issue39689 The call: struct.unpack('>?', b'\xf0') means to unpack a "native bool", i.e. native size and alignment. Internally, this does: static PyObject * nu_bool(const char *p, const formatdef *f) { _Bool x; memcpy((char *)&x, p, sizeof x); return PyBool_FromLong(x != 0); } i.e., copies "sizeof x" (1 byte) of memory to a temporary buffer x, and then treats that as _Bool. While I don't have access to the C standard, I believe it says that assignment of a true value to _Bool can coerce to a unique "true" value. It seems that if a char doesn't have the exact bit pattern for true or false, casting to _Bool is undefined behavior. Is that correct? Clang 10 on s390x seems to take advantage of this: it probably only looks at the last bit(s) so a _Bool with a bit pattern of 0xf0 turns out false. But the tests assume that 0xf0 should unpack to True. -- Regards, Charalampos Stratakis Software Engineer Python Maintenance Team, Red Hat

3 3

3.7.7 schedule accelerated, cutoff now 2020-03-02
by Ned Deily 26 Feb '20

26 Feb '20

https://discuss.python.org/t/3-7-7-schedule-accelerated-cutoff-now-2020-03-… -- Ned Deily nad(a)python.org -- []

1 0

Python 3.8.2 and 3.9.0a4 are now available
by Łukasz Langa 26 Feb '20

26 Feb '20

On behalf of the entire Python development community, and the currently serving Python release team in particular, I’m pleased to announce the release of two of the latest Python editions. Python 3.8.2 Python 3.8.2 is the second maintenance release of Python 3.8 and contains two months worth of bug fixes. Detailed information about all changes made in 3.8.2 can be found in its change log <https://docs.python.org/release/3.8.2/whatsnew/changelog.html#python-3-8-2-…>. Note that compared to 3.8.1, version 3.8.2 also contains the changes introduced in 3.8.2rc1 and 3.8.2rc2. The Python 3.8 series is the newest feature release of the Python language, and it contains many new features and optimizations. You can find Python 3.8.2 here: https://www.python.org/downloads/release/python-382/ <https://www.python.org/downloads/release/python-382/> See the “What’s New in Python 3.8 <https://docs.python.org/3.8/whatsnew/3.8.html>” document for more information about features included in the 3.8 series. Maintenance releases for the 3.8 series will continue at regular bi-monthly intervals, with 3.8.3 planned for April 2020 (at the PyCon US sprints <https://us.pycon.org/2020/events/sprints/>). Python 3.9.0a4 An early developer preview of Python 3.9 is also ready: https://www.python.org/downloads/release/python-390a4/ <https://www.python.org/downloads/release/python-390a4/> Python 3.9 is still in development. This releasee, 3.9.0a4 is the fourth of six planned alpha releases. Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process. During the alpha phase, features may be added up until the start of the beta phase (2020-05-18) and, if necessary, may be modified or deleted up until the release candidate phase (2020-08-10). Please keep in mind that this is a preview release and its use is not recommended for production environments. We hope you enjoy both! Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation. https://www.python.org/psf/ <https://www.python.org/psf/> Your friendly release team, Ned Deily Steve Dower Łukasz Langa

1 0

PEP 614: Relaxing Grammar Restrictions On Decorators
by Brandt Bucher 23 Feb '20

23 Feb '20

PEP 614 has recently completed a round of review on Python-Ideas: https://www.python.org/dev/peps/pep-0614/ It proposes that the current decorator syntax restrictions be relaxed to allow any valid expression. Nobody has raised any objections, but I wanted to gather more feedback here prior to bringing it before the Steering Council. Please let me know what you think... thanks! :)

2 2

Comments on PEP 558 (Defined semantics for locals() )
by Mark Shannon 22 Feb '20

22 Feb '20

Hi, First of all I want to say that I'm very much in favour of the general idea behind PEP 558. Defined semantics is always better than undefined semantics :) However, I think there are a few changes needed: 1. Don't add anything to the C API, please. Frame attributes can be accessed via `PyObject_GetAttr[String]`. 2. Don't make the behaviour dependent on whether "tracing" is turned on. Doing so forces debuggers to use sys.settrace which is horribly slow. It also makes the implementation more complex, and has no benefit AFAICT. 3. Don't store write-through proxies in the frame, but make proxies retain a reference to the frame. This would reduce the size and complexity of code for handling frames. Clean up of the frame would occur naturally via reference count when all proxies have been reclaimed. The proposed implementation is hard to reason about and I am not confident that it will not introduce some new subtle bugs to replace the ones it seeks to remove. Any implementation that has functions with "Borrow" and "BreakCycles" in their names makes me nervous. A simpler conceptual model, which I believe could be made reliable, would be: No change for non-function frames (as PEP 558 currently proposes). Each access to `frame.f_locals` (for function frames) should return a new proxy object. This proxy object would have dict-like, write-through semantics for variables in the frame. For keys that do not match variable names, an exception would be raised. This means that all proxies for a single frame will have value equivalence; object equivalence is not needed. I.e. for a frame `f`, `f.f_locals == f.f_locals` would be True, even though `f.f_locals is f.f_locals` would be False. Cheers, Mark.

2 6

Summary of Python tracker Issues
by Python tracker 21 Feb '20

21 Feb '20

ACTIVITY SUMMARY (2020-02-14 - 2020-02-21) Python tracker at https://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 7315 (+38) closed 44150 (+43) total 51465 (+81) Open issues with patches: 2874 Issues opened (62) ================== #38691: importlib: PYTHONCASEOK should be ignored when using python3 - https://bugs.python.org/issue38691 reopened by vstinner #39636: Can't change Treeview row color in Tkinter https://bugs.python.org/issue39636 opened by Олег Париев #39638: Keep ASDL signatures for AST nodes https://bugs.python.org/issue39638 opened by BTaskaya #39639: Remove Suite node from AST https://bugs.python.org/issue39639 opened by BTaskaya #39640: fall back os.fdatasync() to fsync() on POSIX systems without f https://bugs.python.org/issue39640 opened by gmelikov #39642: Behaviour of disabled widgets: widget.bind(func) -vs- w = https://bugs.python.org/issue39642 opened by mrshr3d #39643: Python calls newfstatat for "<frozen importlib._bootstrap>" in https://bugs.python.org/issue39643 opened by Ivan Babrou #39645: Expand concurrent.futures.Future's public API https://bugs.python.org/issue39645 opened by aeros #39648: Update math.gcd() to accept "n" arguments. https://bugs.python.org/issue39648 opened by Ananthakrishnan #39649: bdb.Bdb.format_stack_entry: checks for obsolete __args__ https://bugs.python.org/issue39649 opened by blueyed #39650: Creating zip file where names in local header don't match with https://bugs.python.org/issue39650 opened by pmqs #39651: Exceptions raised by EventLoop.call_soon_threadsafe https://bugs.python.org/issue39651 opened by Ben.Darnell #39652: sqlite3 bug handling column names that contain square braces https://bugs.python.org/issue39652 opened by simonw #39653: test_posix fails during make test https://bugs.python.org/issue39653 opened by jaguardown #39654: pyclbr: remove old references to class browser & add explain r https://bugs.python.org/issue39654 opened by hakancelik #39656: shebanged scripts can escape from `venv` depending on how it w https://bugs.python.org/issue39656 opened by Anthony Sottile #39657: Bezout and Chinese Remainder Theorem in the Standard Library? https://bugs.python.org/issue39657 opened by Dennis Sweeney #39658: Include user scripts folder to PATH on Windows https://bugs.python.org/issue39658 opened by lucatrv #39659: pathlib calls `os.getcwd()` without using accessor https://bugs.python.org/issue39659 opened by barneygale #39660: Contextvars: Optional callbacks on state change https://bugs.python.org/issue39660 opened by leezu #39663: IDLE: Add additional tests for pyparse https://bugs.python.org/issue39663 opened by cheryl.sabella #39664: Improve test coverage for operator module https://bugs.python.org/issue39664 opened by xtreak #39665: Cryptic error message when creating types that don't include t https://bugs.python.org/issue39665 opened by ppperry #39666: IDLE: Factor out similar code in editor and hyperparser https://bugs.python.org/issue39666 opened by cheryl.sabella #39667: Update zipfile.Path with zipp 3.0 https://bugs.python.org/issue39667 opened by jaraco #39670: 2to3 fix_apply tries to fix user-defined apply function calls https://bugs.python.org/issue39670 opened by ilya #39671: Mention in docs that asyncio.FIRST_COMPLETED does not guarante https://bugs.python.org/issue39671 opened by tom.pohl #39672: SIGSEGV crash on shutdown with shelve & c pickle https://bugs.python.org/issue39672 opened by zd nex #39673: Map errno==ETIME to TimeoutError https://bugs.python.org/issue39673 opened by YoSTEALTH #39674: Keep deprecated features in Python 3.9 to ease migration from https://bugs.python.org/issue39674 opened by vstinner #39675: forked process in multiprocessing does not honour atexit https://bugs.python.org/issue39675 opened by gaborbernat #39677: 3.6+ documentation for MAKE_FUNCTION https://bugs.python.org/issue39677 opened by thautwarm #39678: RFC improve readability of _queue_management_worker for Proces https://bugs.python.org/issue39678 opened by tomMoral #39679: functools: singledispatchmethod doesn't work with classmethod https://bugs.python.org/issue39679 opened by Viktor Roytman #39680: datetime.astimezone() method does not handle invalid local tim https://bugs.python.org/issue39680 opened by belopolsky #39681: pickle.load expects an object that implements readinto https://bugs.python.org/issue39681 opened by Nathan.Goldbaum #39682: pathlib.Path objects can be used as context managers https://bugs.python.org/issue39682 opened by barneygale #39683: 2to3 fix_exitfunc suggests duplicated import of atexit module https://bugs.python.org/issue39683 opened by ilya #39685: Python 3.8 regression Socket operation on non-socket https://bugs.python.org/issue39685 opened by brian #39686: add dump_json to ast module https://bugs.python.org/issue39686 opened by sparverius #39688: tarfile: GNU sparse 1.0 pax tar header offset not properly com https://bugs.python.org/issue39688 opened by Nit #39689: test_struct failure on s390x Fedora Clang buildbot https://bugs.python.org/issue39689 opened by cstratak #39690: Compiler warnings in unicodeobject.c https://bugs.python.org/issue39690 opened by serhiy.storchaka #39691: Allow passing Pathlike objects to io.open_code https://bugs.python.org/issue39691 opened by kmaork #39692: Subprocess using list vs string https://bugs.python.org/issue39692 opened by nik-sm #39693: tarfile's extractfile documentation is misleading https://bugs.python.org/issue39693 opened by josh.r #39694: Incorrect dictionary unpacking when calling str.format https://bugs.python.org/issue39694 opened by Akos Kiss #39697: Failed to build with --with-cxx-main=g++-9.2.0 https://bugs.python.org/issue39697 opened by Marco Sulla #39699: Some CIs silence potentially useful output from make https://bugs.python.org/issue39699 opened by ammar2 #39700: asyncio.selector_events._SelectorTransport: Add logging when s https://bugs.python.org/issue39700 opened by dsternlicht #39701: Azure Pipelines PR broken https://bugs.python.org/issue39701 opened by skrah #39702: PEP 614: Relaxing Grammar Restrictions On Decorators https://bugs.python.org/issue39702 opened by brandtbucher #39704: Disable code coverage https://bugs.python.org/issue39704 opened by skrah #39705: Tutorial, 5.6 Looping Techniques, sorted() example https://bugs.python.org/issue39705 opened by mirwi #39706: unittest.IsolatedAsyncioTestCase hangs on asyncio.CancelledErr https://bugs.python.org/issue39706 opened by Andrey Moiseev #39707: Abstract property setter/deleter implementation not enforced. https://bugs.python.org/issue39707 opened by arn.vollebregt.kpn #39708: final link stage in compile fails for 3.8.1 with missing CFLAG https://bugs.python.org/issue39708 opened by blastwave #39709: missing CFLAGS during make tests results in test and compile f https://bugs.python.org/issue39709 opened by blastwave #39710: "will be returned as unicode" reminiscent from Python 2 https://bugs.python.org/issue39710 opened by mdk #39711: SIGBUS and core dumped during tests of 3.8.1 https://bugs.python.org/issue39711 opened by blastwave #39712: Doc for `-X dev` option should mention PYTHONDEVMODE https://bugs.python.org/issue39712 opened by pitrou #39714: ElementTree limitation https://bugs.python.org/issue39714 opened by Ananth Vijalapuram Most recent 15 issues with no replies (15) ========================================== #39714: ElementTree limitation https://bugs.python.org/issue39714 #39712: Doc for `-X dev` option should mention PYTHONDEVMODE https://bugs.python.org/issue39712 #39711: SIGBUS and core dumped during tests of 3.8.1 https://bugs.python.org/issue39711 #39710: "will be returned as unicode" reminiscent from Python 2 https://bugs.python.org/issue39710 #39709: missing CFLAGS during make tests results in test and compile f https://bugs.python.org/issue39709 #39708: final link stage in compile fails for 3.8.1 with missing CFLAG https://bugs.python.org/issue39708 #39706: unittest.IsolatedAsyncioTestCase hangs on asyncio.CancelledErr https://bugs.python.org/issue39706 #39702: PEP 614: Relaxing Grammar Restrictions On Decorators https://bugs.python.org/issue39702 #39700: asyncio.selector_events._SelectorTransport: Add logging when s https://bugs.python.org/issue39700 #39693: tarfile's extractfile documentation is misleading https://bugs.python.org/issue39693 #39691: Allow passing Pathlike objects to io.open_code https://bugs.python.org/issue39691 #39685: Python 3.8 regression Socket operation on non-socket https://bugs.python.org/issue39685 #39683: 2to3 fix_exitfunc suggests duplicated import of atexit module https://bugs.python.org/issue39683 #39682: pathlib.Path objects can be used as context managers https://bugs.python.org/issue39682 #39680: datetime.astimezone() method does not handle invalid local tim https://bugs.python.org/issue39680 Most recent 15 issues waiting for review (15) ============================================= #39702: PEP 614: Relaxing Grammar Restrictions On Decorators https://bugs.python.org/issue39702 #39700: asyncio.selector_events._SelectorTransport: Add logging when s https://bugs.python.org/issue39700 #39699: Some CIs silence potentially useful output from make https://bugs.python.org/issue39699 #39688: tarfile: GNU sparse 1.0 pax tar header offset not properly com https://bugs.python.org/issue39688 #39686: add dump_json to ast module https://bugs.python.org/issue39686 #39681: pickle.load expects an object that implements readinto https://bugs.python.org/issue39681 #39678: RFC improve readability of _queue_management_worker for Proces https://bugs.python.org/issue39678 #39677: 3.6+ documentation for MAKE_FUNCTION https://bugs.python.org/issue39677 #39674: Keep deprecated features in Python 3.9 to ease migration from https://bugs.python.org/issue39674 #39667: Update zipfile.Path with zipp 3.0 https://bugs.python.org/issue39667 #39666: IDLE: Factor out similar code in editor and hyperparser https://bugs.python.org/issue39666 #39664: Improve test coverage for operator module https://bugs.python.org/issue39664 #39663: IDLE: Add additional tests for pyparse https://bugs.python.org/issue39663 #39654: pyclbr: remove old references to class browser & add explain r https://bugs.python.org/issue39654 #39652: sqlite3 bug handling column names that contain square braces https://bugs.python.org/issue39652 Top 10 most discussed issues (10) ================================= #39648: Update math.gcd() to accept "n" arguments. https://bugs.python.org/issue39648 20 msgs #39576: Surprising MemoryError in `decimal` with MAX_PREC https://bugs.python.org/issue39576 10 msgs #38691: importlib: PYTHONCASEOK should be ignored when using python3 - https://bugs.python.org/issue38691 8 msgs #39673: Map errno==ETIME to TimeoutError https://bugs.python.org/issue39673 8 msgs #39694: Incorrect dictionary unpacking when calling str.format https://bugs.python.org/issue39694 8 msgs #39573: Make PyObject an opaque structure in the limited C API https://bugs.python.org/issue39573 7 msgs #39704: Disable code coverage https://bugs.python.org/issue39704 7 msgs #12915: Add inspect.locate and inspect.resolve https://bugs.python.org/issue12915 6 msgs #39686: add dump_json to ast module https://bugs.python.org/issue39686 6 msgs #39622: KeyboardInterrupt is ignored when await asyncio.sleep(0) https://bugs.python.org/issue39622 5 msgs Issues closed (40) ================== #9056: Adding additional level of bookmarks and section numbers in py https://bugs.python.org/issue9056 closed by mdk #9495: argparse unittest tracebacks are confusing if an error is rais https://bugs.python.org/issue9495 closed by taleinat #19660: decorator syntax: allow testlist instead of just dotted_name https://bugs.python.org/issue19660 closed by brandtbucher #27873: multiprocessing.pool.Pool.map should take more than one iterab https://bugs.python.org/issue27873 closed by aeros #32352: `inspect.getfullargspec` doesn't work fine for some builtin ca https://bugs.python.org/issue32352 closed by thautwarm #35727: sys.exit() in a multiprocessing.Process does not align with Py https://bugs.python.org/issue35727 closed by pitrou #35950: io.BufferedReader.writabe is False, but io.BufferedReader.trun https://bugs.python.org/issue35950 closed by inada.naoki #39104: ProcessPoolExecutor hangs on shutdown nowait with pickling fai https://bugs.python.org/issue39104 closed by pitrou #39245: Public API for Vectorcall (PEP 590) https://bugs.python.org/issue39245 closed by petr.viktorin #39432: Distutils generates the wrong export symbol for unicode module https://bugs.python.org/issue39432 closed by scoder #39453: Use-after-free in list contain https://bugs.python.org/issue39453 closed by vstinner #39479: [RFE] Add math.lcm() function: Least Common Multiple https://bugs.python.org/issue39479 closed by mark.dickinson #39540: Logging docs don't address the creation of multiple loggers wh https://bugs.python.org/issue39540 closed by vinay.sajip #39572: [typing] TypedDict's 'total' argument is undocumented https://bugs.python.org/issue39572 closed by gvanrossum #39589: Logging QueueListener should support context manager https://bugs.python.org/issue39589 closed by vinay.sajip #39611: PyVectorcall_NARGS(): change return type to Py_ssize_t https://bugs.python.org/issue39611 closed by petr.viktorin #39618: logger.exception with default message https://bugs.python.org/issue39618 closed by vinay.sajip #39623: __str__ and __repr__ for asyncio.Task still omit arg values https://bugs.python.org/issue39623 closed by yselivanov #39628: msg.walk memory leak? https://bugs.python.org/issue39628 closed by falon #39633: venv does not include python<major>.<minor> symlink by default https://bugs.python.org/issue39633 closed by vinay.sajip #39634: Add clarification in documentation for heapq.heapify naming https://bugs.python.org/issue39634 closed by rhettinger #39635: One paragraph of the doc is not translated in French https://bugs.python.org/issue39635 closed by mdk #39637: Probably incorrect message after failed import https://bugs.python.org/issue39637 closed by vanrein #39641: concatenation of Tuples https://bugs.python.org/issue39641 closed by steven.daprano #39644: Add Binary module. https://bugs.python.org/issue39644 closed by mark.dickinson #39646: compile warning in unicodeobject.c https://bugs.python.org/issue39646 closed by vstinner #39647: Update doc of init_config.rst https://bugs.python.org/issue39647 closed by vstinner #39655: Shared_Memory attaching to incorrect Address in Windows 10 https://bugs.python.org/issue39655 closed by eryksun #39661: TimedRotatingFileHandler doesn’t handle DST switch with dail https://bugs.python.org/issue39661 closed by snoopyjc #39662: Characters are garbled when displaying Byte data https://bugs.python.org/issue39662 closed by eric.smith #39668: segmentation fault on calling __reversed__() https://bugs.python.org/issue39668 closed by xtreak #39669: macOS test failures https://bugs.python.org/issue39669 closed by vstinner #39676: test_shutil fails with OSError: [Errno 28] No space left on de https://bugs.python.org/issue39676 closed by petr.viktorin #39684: PyUnicode_IsIdentifier has two if/thens that can be combined https://bugs.python.org/issue39684 closed by benjamin.peterson #39687: re.sub behaves inconsistent between versions with * repetition https://bugs.python.org/issue39687 closed by serhiy.storchaka #39695: Failed to build _uuid module, but libraries was installed https://bugs.python.org/issue39695 closed by ammar2 #39696: Failed to build _ssl module, but libraries was installed https://bugs.python.org/issue39696 closed by ammar2 #39698: asyncio.sleep() does not adhere to time.sleep() behavior for n https://bugs.python.org/issue39698 closed by yselivanov #39703: Floor division operator and floats https://bugs.python.org/issue39703 closed by mark.dickinson #39713: ElementTree limitation https://bugs.python.org/issue39713 closed by Ananth Vijalapuram

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