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Python 3.9.0b1

Release Date: May 19, 2020

This is a beta preview of Python 3.9

Python 3.9 is still in development. This release, 3.9.0b1, is the first 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 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 3.9.0b2. It is currently scheduled for 2020-06-08.

More resources

And now for something completely different

Mr Vernon (Eric Idle): Hello, madam. (comes in)
Mrs Long Name (Terry Jones): Ah hello... you must have come about...
Mr Vernon: Finishing the sentences, yes.
Mrs Long Name: Oh... well... perhaps you'd like to...
Mr Vernon: Come through this way, certainly. (they go through into the sitting room) Oh, nice place you've got here.
Mrs Long Name: Yes ... well ... er... we...
Mr Vernon: Like it?
Mrs Long Name: Yes ... yes we certainly...
Mr Vernon: Do... Good! Now then, when did you first start...
Mrs Long Name: ...finding it difficult to...
Mr Vernon: Finish sentences, yes.
Mrs Long Name: Well it's not me, it's my...
Mr Vernon: Husband?
Mrs Long Name: Yes. He...
Mr Vernon: Never lets you finish what you've started.
Mrs Long Name: Quite. I'm beginning to feel...
Mr Vernon: That you'll never finish a sentence again as long as you live.
Mrs Long Name: Exact...
Mr Vernon: ly. It must be awful.

Full Changelog


Version Operating System Description MD5 Sum File Size GPG
Gzipped source tarball Source release ad2fff4612992c1b3058aa815d019427 23.7 MB SIG
XZ compressed source tarball Source release 0001c61e8dc664f19249c7af05e966f8 17.6 MB SIG
macOS 64-bit installer macOS for OS X 10.9 and later 19a6ff889c8dfa83af7eaa3235a75f59 28.6 MB SIG
Windows help file Windows d5cb032509efa2142e950fcb67b0f403 8.4 MB SIG
Windows x86 embeddable zip file Windows e5190043b3646c92dc3ac7aebcded11a 7.2 MB SIG
Windows x86 executable installer Windows 4a1c4d7f993aa20ded3e4b8be2cc526a 26.0 MB SIG
Windows x86 web-based installer Windows 538c5c9e7eff65b22244ddc3071694c1 1.3 MB SIG
Windows x86-64 embeddable zip file Windows for AMD64/EM64T/x64 6773f81c723389b83577c1aa27c47844 8.0 MB SIG
Windows x86-64 executable installer Windows for AMD64/EM64T/x64 7f86d52a006ffe1b676797c16af82750 27.0 MB SIG
Windows x86-64 web-based installer Windows for AMD64/EM64T/x64 10293de2cb51f2171a60494dab50e759 1.3 MB SIG