Release Date: June 9, 2020

WARNING: this release has a known regression

See BPO-40924 for details. Use Python 3.9.0b3 or newer instead, please.

This is a beta preview of Python 3.9

Python 3.9 is still in development. This release, 3.9.0b2, is the second of four 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 4 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 Łukasz know.)

The next pre-release, the second beta release of Python 3.9, will be 3.9.0b3. It is currently scheduled for 2020-06-29.

More resources

• Online Documentation
• PEP 596, 3.9 Release Schedule
• Report bugs at https://bugs.python.org.
• Help fund Python and its community.

And now for something completely different

Mrs Concrete (Terry Jones): Oh yes, we've been expecting you.
Ratcatcher (Graham Chapman): I gather you've got a little rodental problem.
Mrs Concrete: Oh, blimey. You'd think he was awake all the night, scrabbling down by the wainscotting.
Ratcatcher: Um, that's an interesting word, isn't it?
Mrs Concrete: What?
Ratcatcher: Wainscotting ... Wainscotting ... Wainscotting ... sounds like a little Dorset village, doesn't it? Wainscotting.
Ratcatcher: Now, where is it worst?
Mrs Concrete: Well, down here. You can usually hear them.
(Indicates base of wall, which has a label on it saying 'Wainscotting'.)
Ratcatcher: Sssssh
Voice Over: Baa ... baa ... baa ... baa ... baa ... baa...
Ratcatcher: No, that's sheep you've got there.
Voice Over: Baa ... baa.
Ratcatcher: No, that's definitely sheep. A bit of a puzzle, really.
Mrs Concrete: Is it?
Ratcatcher: Yeah, well, I mean it's a) not going to respond to a nice piece of cheese and b) it isn't going to fit into a trap.

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