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Python 3.9.0b4

Release Date: July 3, 2020

This is a beta preview of Python 3.9

Python 3.9 is still in development. This release, 3.9.0b4, is the fourth of five planned beta release previews. Beta release previews are intended to give the wider community the opportunity to test new features and bug fixes and to prepare their projects to support the new feature release.

Call to action

We strongly encourage maintainers of third-party Python projects to test with 3.9 during the beta phase and report issues found to the Python bug tracker as soon as possible. While the release is planned to be feature complete entering the beta phase, it is possible that features may be modified or, in rare cases, deleted up until the start of the release candidate phase (2020-08-10). Our goal is have no ABI changes after beta 5 and as few code changes as possible after 3.9.0rc1, the first release candidate. To achieve that, it will be extremely important to get as much exposure for 3.9 as possible during the beta phase.

Please keep in mind that this is a preview release and its use is not recommended for production environments.

Major new features of the 3.9 series, compared to 3.8

Some of the new major new features and changes in Python 3.9 are:

  • PEP 584, Union Operators in dict
  • PEP 585, Type Hinting Generics In Standard Collections
  • PEP 593, Flexible function and variable annotations
  • PEP 602, Python adopts a stable annual release cadence
  • PEP 615, Support for the IANA Time Zone Database in the Standard Library
  • PEP 616, String methods to remove prefixes and suffixes
  • PEP 617, New PEG parser for CPython
  • BPO 38379, garbage collection does not block on resurrected objects;
  • BPO 38692, os.pidfd_open added that allows process management without races and signals;
  • BPO 39926, Unicode support updated to version 13.0.0;
  • BPO 1635741, when Python is initialized multiple times in the same process, it does not leak memory anymore;
  • A number of Python builtins (range, tuple, set, frozenset, list, dict) are now sped up using PEP 590 vectorcall;
  • A number of Python modules (_abc, audioop, _bz2, _codecs, _contextvars, _crypt, _functools, _json, _locale, operator, resource, time, _weakref) now use multiphase initialization as defined by PEP 489;
  • A number of standard library modules (audioop, ast, grp, _hashlib, pwd, _posixsubprocess, random, select, struct, termios, zlib) are now using the stable ABI defined by PEP 384.

  • (Hey, fellow core developer, if a feature you find important is missing from this list, let Ɓukasz know.)

The next pre-release, the fifth beta release of Python 3.9, will be 3.9.0b5. It is currently scheduled for 2020-07-20.

More resources

And now for something completely different

(Cut to a newsreader in a 'News at Nine' set with a bare lightbulb hanging in shot. He wears only an old blanket around his shoulders. He is shivering.)

Newsreader (Eric Idle): The BBC wishes to deny rumours that it is going into liquidation. Mrs Kelly, who owns the flat where they live, has said that they can stay on till the end of the month...
(he is handed a piece of paper)
Newsreader: ...and we've just heard that Hugh Weldon's watch has been accepted by the London Electricity Board and transmissions for this evening can be continued as planned.
(he coughs and pulls the blanket tighter round his shoulders)
Newsreader: That's all from me so... goodnight.

Full Changelog

Files

Version Operating System Description MD5 Sum File Size GPG
Gzipped source tarball Source release 87fb911cbf7ac06819e016d6c04a448d 25023724 SIG
XZ compressed source tarball Source release 3c9f7aea301d27790c82df06ecce8850 18602256 SIG
macOS 64-bit installer Mac OS X for OS X 10.9 and later 365dc1d4b6390a6fa679d739b5b68c7e 30186810 SIG
Windows help file Windows 2daccbb69f7d0fb6398be70f63fe85fb 8731717 SIG
Windows x86-64 embeddable zip file Windows for AMD64/EM64T/x64 35fdd9bc10fe2d6bfb13beae52407243 8383310 SIG
Windows x86-64 executable installer Windows for AMD64/EM64T/x64 22a373c859b02664816852bd9c85d042 28367704 SIG
Windows x86-64 web-based installer Windows for AMD64/EM64T/x64 4dd6b84dd8068250d2018508f7708950 1364464 SIG
Windows x86 embeddable zip file Windows 09a598d0af4e9a5710f7a328484850e4 7555411 SIG
Windows x86 executable installer Windows 01bb9cab4d9ebb9062395c2c4bbed938 27288800 SIG
Windows x86 web-based installer Windows 510e6d8814bb2d63915c0bcb1ec9a4b0 1328456 SIG