Python 3.13.0 beta 3 now available

The next to last Python 3.13 beta version, beta 3, is now released:

This is a beta preview of Python 3.13

Python 3.13 is still in development. This release, 3.13.0b3, is the third of four beta release previews of 3.13.

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.

We strongly encourage maintainers of third-party Python projects to test with 3.13 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 (Tuesday 2024-07-30). Our goal is to have no ABI changes after beta 4 and as few code changes as possible after 3.13.0rc1, the first release candidate. To achieve that, it will be extremely important to get as much exposure for 3.13 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 3.13 series, compared to 3.12

Some of the new major new features and changes in Python 3.13 are:

New features

  • A new and improved interactive interpreter, based on PyPy’s, featuring multi-line editing and color support, as well as colorized exception tracebacks.
  • An experimental free-threaded build mode, which disables the Global Interpreter Lock, allowing threads to run more concurrently. The build mode is available as an experimental feature in the Windows and macOS installers as well.
  • A preliminary, experimental JIT, providing the ground work for significant performance improvements.
  • The (cyclic) garbage collector is now incremental, which should mean shorter pauses for collection in programs with a lot of objects.
  • A modified version of mimalloc is now included, optional but enabled by default if supported by the platform, and required for the free-threaded build mode.
  • Docstrings now have their leading indentation stripped, reducing memory use and the size of .pyc files. (Most tools handling docstrings already strip leading indentation.)
  • The dbm module has a new dbm.sqlite3 backend that is used by default when creating new files.
  • The minimum supported macOS version was changed from 10.9 to 10.13 (High Sierra). Older macOS versions will not be supported going forward.

Typing

Removals and new deprecations

  • PEP 594 (Removing dead batteries from the standard library) scheduled removals of many deprecated modules: aifc, audioop, chunk, cgi, cgitb, crypt, imghdr, mailcap, msilib, nis, nntplib, ossaudiodev, pipes, sndhdr, spwd, sunau, telnetlib, uu, xdrlib, lib2to3.
  • Many other removals of deprecated classes, functions and methods in various standard library modules.
  • C API removals and deprecations. (Some removals present in alpha 1 were reverted in alpha 2, as the removals were deemed too disruptive at this time.)
  • New deprecations, most of which are scheduled for removal from Python 3.15 or 3.16.

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

For more details on the changes to Python 3.13, see What’s new in Python 3.13. The next pre-release of Python 3.13 will be 3.13.0b4, currently scheduled for 2024-07-16.

More resources

Enjoy the new releases

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.

Regards from scorchingly hot Amsterdam (hey, we get good weather too!),

Your release team,
Thomas Wouters @thomas
Łukasz Langa @ambv
Ned Deily @nad
Steve Dower @steve.dower

11 Likes

Am I correct in assuming that it’ll use Unicode 15.1 because it’ll be way too late for Unicode 16.0, which is due out in September 2024?

2 Likes

WASI build at Release CPython 3.13.0b3 w/ WASI SDK 21 · brettcannon/cpython-wasi-build · GitHub .

2 Likes

This beta is using 15.1 (you can check with unicodedata.unidata_version on any Python version, as as we’re past the feature freeze point now I wouldn’t expect that to change before 3.13.0 final.

Yes, Unicode 16 arrives about five months too late to make it into Python 2024 (3.13) I’m afraid.

Fedora updates are now available Fedora Updates System

3 Likes

I built python 3.13.0b3 on Arch linux in the same way as python 3.12.4.

I notice a change in the repl apart from the obvious colour changes.

In 3.12.4 the repl history extends back in time to previous usage of python
so up arrow brings back statements from a previous run.

In python 3.13.0b3 the up arrow doesn’t seem to bring back statements from
the previous python run. I checked with my previous build of python 3.13.0b2
and it seems this is a change between 3.13.0b2 and b3.

Is there some change in the way I need to build python 3.13 or is
there a way to recover this useful behaviour.

EDIT: I find that python 3.13.0b3 can see history of previous runs of different pythons, but seems to clear history at exit.

I just tried this on Ubuntu 22.04. The first time Python 3.13 runs the history is there, but after exiting and starting it again there’s no history.

I did find this issue regarding a startup file to load the history. But I’m seeing the issue without one.

I suggest to open an issue for the REPL which fails to save the command history.

I think this is the same issue as mentioned by domdfcoding above. As noted there it seems to be the code at site.py line 527 write_history that fails; domdfcoding mentioned a couple of possible fixes and I tried the one that modifies site.py and as he says need to refix the frozen lib before it becomes active.

I reported:

3 Likes