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Python 3.10.0rc2

Release Date: Sept. 7, 2021

This is the first release candidate of Python 3.10

This release, 3.10.0rc2, is the last preview before the final release of Python 3.10.0 on 2021-10-04. Entering the release candidate phase, only reviewed code changes which are clear bug fixes are allowed between release candidates and the final release. There will be no ABI changes from this point forward in the 3.10 series and the goal is that there will be as few code changes as possible.

Call to action

We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.10 compatibility during this phase. As always, report any issues to the Python bug tracker.

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

Major new features of the 3.10 series, compared to 3.9

Many new features for Python 3.10 are still being planned and written. Among the new major new features and changes so far:

  • PEP 623 -- Deprecate and prepare for the removal of the wstr member in PyUnicodeObject.
  • PEP 604 -- Allow writing union types as X | Y
  • PEP 612 -- Parameter Specification Variables
  • PEP 626 -- Precise line numbers for debugging and other tools.
  • PEP 618 -- Add Optional Length-Checking To zip.
  • bpo-12782: Parenthesized context managers are now officially allowed.
  • PEP 632 -- Deprecate distutils module.
  • PEP 613 -- Explicit Type Aliases
  • PEP 634 -- Structural Pattern Matching: Specification
  • PEP 635 -- Structural Pattern Matching: Motivation and Rationale
  • PEP 636 -- Structural Pattern Matching: Tutorial
  • PEP 644 -- Require OpenSSL 1.1.1 or newer
  • PEP 624 -- Remove Py_UNICODE encoder APIs
  • PEP 597 -- Add optional EncodingWarning

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

The next release will be the final release of Python 3.10.0, which is currently scheduled for Monday, 2021-10-04.

bpo-38605: from __future__ import annotations (PEP 563) used to be on this list in previous pre-releases but it has been postponed to Python 3.11 due to some compatibility concerns. You can read the Steering Council communication about it here to learn more.

More resources

And now for something completely different

Maxwell's demon is a thought experiment that would hypothetically violate the second law of thermodynamics. It was proposed by the physicist James Clerk Maxwell in 1867. In the thought experiment, a demon controls a small massless door between two chambers of gas. As individual gas molecules (or atoms) approach the door, the demon quickly opens and closes the door to allow only fast-moving molecules to pass through in one direction, and only slow-moving molecules to pass through in the other. Because the kinetic temperature of a gas depends on the velocities of its constituent molecules, the demon's actions cause one chamber to warm up and the other to cool down. This would decrease the total entropy of the two gases, without applying any work, thereby violating the second law of thermodynamics.

Full Changelog


Version Operating System Description MD5 Sum File Size GPG
Gzipped source tarball Source release 55652b94990d6bf15fe1e47ac1114519 25002890 SIG
XZ compressed source tarball Source release d3bfe8004516dd5b2afc649ff94be965 18737220 SIG
macOS 64-bit universal2 installer macOS for macOS 10.9 and later, including macOS 11 Big Sur on Apple Silicon (experimental) fada6b331699e922efbc1c1c0c6197f8 39725608 SIG
Windows embeddable package (32-bit) Windows 011d61255bf242a5e10e6cd754710148 7522032 SIG
Windows embeddable package (64-bit) Windows 29f66c41e13ca02bfb86a20260610f63 8475522 SIG
Windows help file Windows 7c34a6f4e89d5aa308edacb23322f666 9567441 SIG
Windows installer (32-bit) Windows acbd60da86d3cc001e9ccbe7366b51f9 27201184 SIG
Windows installer (64-bit) Windows Recommended b49614e82253d9ffe3f75f35aefff7eb 28325752 SIG