Python 3.11 Release Notes

Release Date: October 24, 2022

Python 3.11 is a major release focused on performance, error reporting, and developer experience improvements.

What's New in Python 3.11

Performance Improvements

Python 3.11 is 10–60% faster than Python 3.10 on average.

• New specializing adaptive interpreter:
  • Dynamically optimizes bytecode based on runtime behavior.
• Faster function calls and reduced overhead.
• “Zero-cost” exceptions:
  • No performance penalty unless an exception is raised.
• Reduced memory usage for frames and objects.

Language and Exceptions

• PEP 654: Exception Groups and except*:

  • Handle multiple exceptions at once (useful for async/concurrent code). :contentReference[oaicite:0]{index=0}

• PEP 678: Exceptions can include notes:

  • Add additional context to errors.

• PEP 657: Precise error locations:

  • Tracebacks highlight exact expression positions. :contentReference[oaicite:1]{index=1}

Error Messages

• More informative and precise tracebacks.
• Better suggestions for common mistakes (e.g. NameError, AttributeError).
• Improved debugging experience overall.

Typing Improvements

• PEP 673: Self type for cleaner class method annotations.
• PEP 646: Variadic generics.
• PEP 655: Required / NotRequired fields in TypedDict.
• PEP 675: Arbitrary literal string types.
• PEP 681: Data class transforms. :contentReference[oaicite:2]{index=2}

Standard Library

• New module tomllib:

  • Native read-only TOML parsing.

• Improvements to re:

  • Support for atomic grouping (?>...).
  • Faster regex execution.

• Many updates across standard library modules.

Other Improvements

• Better debugging support (accurate line numbers, PEP 626).
• Improved startup time and internal optimizations.
• Experimental WebAssembly support groundwork.

Deprecations

• Start of removing legacy modules ("dead batteries") (PEP 594).
• Ongoing cleanup of deprecated APIs.

Migration Guide

When upgrading from Python 3.10:

• Most code works without changes.
• Review new warnings and deprecated modules.
• Test async and exception-heavy code for new behavior.

Documentation

Official 3.11 documentation