Release Date: Nov. 15, 2021

This is the eighth maintenance release of Python 3.9

Note: The release you're looking at is Python 3.9.9, an expedited bugfix release for the legacy 3.9 series. Python 3.10 is now the latest feature release series of Python 3. Get the latest release of 3.10.x here.

3.9.9 was released out of schedule as a hotfix for an argparse regression in Python 3.9.8 which caused complex command-line tools to fail recognizing sub-commands properly. Details in BPO-45235. There are only three other bugfixes in this release compared to 3.9.8. See the changelog for details on what changed.

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 573, Module State Access from C Extension Methods
• 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 614, Relaxing Grammar Restrictions On Decorators
• 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.

You can find a more comprehensive list in this release's "What's New" document.

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

Geppo: Well Reg, I think Pablo should be all right provided he doesn't attempt anything on the monumental scale of some of his earlier paintings, like Guernica or Mademoiselles d'Avignon or even his later War and Peace murals for the Temple of Peace chapel at Vallauris, because with this strong head wind I don't think even Doug Timpson of Manchester Harriers could paint anything on that kind of scale.
Reg Moss: Well, thank you Ron. Well, there still seems to be no sign of Picasso, so I'll hand you back to the studio.
Linkman: Well, we've just heard that Picasso is approaching the Tolworth roundabout on the A3 so come in Sam Trench at Tolworth.
Trench: Well something certainly is happening here at Tolworth roundabout, David. I can now see Picasso, he's cycling down very hard towards the roundabout, he's about 75-50 yards away and I can now see his painting... it's an abstract... I can see some blue some purple and some little black oval shapes... I think I can see...
A Pepperpot comes up and nudges him.
Pepperpot: That's not Picasso - that's Kandinsky.

Full Changelog