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Python 3.13/3.14 Support Plan

Status: Completed Created: 2026-02-03 Issue: mrrc-83m

Executive Summary

This document outlines the plan to update mrrc's Python version support:

  • Add: Python 3.13 (stable, released October 2024)
  • Add: Python 3.14 (stable, released October 2025)
  • Drop: Python 3.9 (reached EOL October 2025)

The changes primarily involve CI/CD configuration updates. No code changes are expected—PyO3 0.27 already supports both versions.

Current State

Supported Versions

  • Python 3.9, 3.10, 3.11, 3.12
  • Platforms: Linux (x86_64, aarch64), macOS (x86_64, arm64), Windows (x86_64)

Key Dependencies

Dependency Version Python Support
PyO3 0.27.x 3.8–3.14, including free-threaded 3.13t/3.14t
maturin >=1.0,<2.0 3.8+

Configuration Files

  • pyproject.toml: requires-python = ">=3.9", classifiers list 3.9–3.12
  • .github/workflows/python-build.yml: matrix includes 3.9–3.12
  • .github/workflows/benchmark-python.yml: matrix includes 3.9–3.12
  • src-python/Cargo.toml: PyO3 0.27 with extension-module feature

Python 3.9 Deprecation

EOL Status

Python 3.9 reached End-of-Life on October 31, 2025. As of February 2026:

  • No security patches from PSF
  • Major platforms have dropped support:
  • AWS Lambda: December 15, 2025
  • Heroku: January 7, 2026
  • Palantir Foundry: February 1, 2026

Recommendation: Drop Python 3.9

Rationale:

  1. Security: No upstream security patches available
  2. Maintenance burden: Testing 6 Python versions increases CI time
  3. User impact: Minimal—most production environments have migrated
  4. Industry alignment: NumPy, pandas, and other major libraries dropped 3.9 in 2025

RHEL 9 Users: RHEL 9 ships Python 3.9 as system default and will maintain it through RHEL 9's lifecycle. Users on RHEL 9 should install Python 3.10+ via dnf module or use containers.

Python 3.13 Support

Status

Python 3.13 was released October 2024 and is now at 3.13.x. Fully stable.

PyO3 Compatibility

PyO3 0.27.x fully supports Python 3.13:

  • Standard builds work out of the box
  • Free-threaded builds (3.13t) supported with Sync requirement on #[pyclass] types
  • ABI3 stable ABI support via abi3-py313 feature

mrrc Compatibility Assessment

Component Status Notes
Core parsing Ready No Python-specific code
PyO3 bindings Ready All types already Send + Sync
GIL release Ready Three-phase pattern unchanged
Format converters Ready No version-specific code

Free-Threaded Python (3.13t/3.14t)

Python 3.13 introduced experimental free-threaded mode (no GIL). mrrc is well-positioned:

  • Rust types are inherently thread-safe
  • GIL release pattern already in use for parallel I/O
  • #[pyclass] types implement Sync (required for free-threaded builds)

Recommendation: Do not officially support free-threaded builds yet. The feature remains experimental and requires opt-in at build time. Revisit when Python 3.15 stabilizes the feature.

Future potential: When free-threading stabilizes, mrrc could simplify its Python wrapper by removing GIL management code (three-phase pattern, BatchedMarcReader queue). The current implementation will continue working on both GIL and free-threaded builds.

Python 3.14 Support

Status

Python 3.14 was released October 7, 2025 (PEP 745) and is now at 3.14.2. Fully stable.

PyO3 Compatibility

PyO3 0.27.x fully supports Python 3.14:

  • Tested against release candidates and stable releases
  • Free-threaded 3.14t support included
  • Edge cases on 32-bit systems addressed

Considerations

  1. C API changes: Some deprecated functions removed, but PyO3 handles this
  2. Build warnings: May see deprecation warnings during compilation (informational only)
  3. maturin support: Fully supported in maturin 1.x

Implementation Plan

Phase 1: Update Version Support

  1. Update pyproject.toml: 

    requires-python = ">=3.10"
classifiers = [
    "Programming Language :: Python :: 3.10",
    "Programming Language :: Python :: 3.11",
    "Programming Language :: Python :: 3.12",
    "Programming Language :: Python :: 3.13",
    "Programming Language :: Python :: 3.14",
]

  2. Update mypy/pyright target version: 

    [tool.mypy]
python_version = "3.10"

[tool.pyright]
pythonVersion = "3.10"

  3. Update CI workflows:

  4. Remove "3.9" from all matrices

  5. Add "3.13" and "3.14" to all matrices

  6. Update documentation (README, installation guide)

Phase 2: Local Verification

Test locally before pushing:

# For each version 3.10, 3.11, 3.12, 3.13, 3.14
uv python install 3.14
uv venv --python 3.14
uv run maturin develop --release
pytest tests/python/ -m "not benchmark" -v

Phase 3: CI Verification

Push changes and verify:

  • All wheel builds succeed on Linux, macOS, Windows
  • All test matrices pass
  • Benchmark results are comparable across versions

Files to Modify

File Change
pyproject.toml Update requires-python, classifiers, mypy/pyright versions
.github/workflows/python-build.yml Update matrix: ["3.10", "3.11", "3.12", "3.13", "3.14"]
.github/workflows/python-release.yml Update matrix: ["3.10", "3.11", "3.12", "3.13", "3.14"]
.github/workflows/benchmark-python.yml Update matrix: ["3.10", "3.11", "3.12", "3.13", "3.14"]
README.md Update supported Python versions
docs/getting-started/installation.md Update minimum version to 3.10
CHANGELOG.md Document version changes in release notes

CI Impact

Change Build Jobs Test Jobs Benchmark Jobs
Remove 3.9 -3 -3 -1
Add 3.13 +3 +3 +1
Add 3.14 +3 +3 +1
Net change +3 +3 +1

Total additional CI time: ~15–20 minutes per PR (parallelized).

Risk Assessment

Risk Likelihood Impact Mitigation
3.13/3.14 build failures Low Medium PyO3 0.27 fully supports both
User complaints (3.9 drop) Low Low 4 months post-EOL; document RHEL 9 workaround
Performance regression on new versions Low Low Benchmark comparison in CI
manylinux compatibility Low Medium Continue using manylinux2014 (glibc 2.17)

Edge Cases

manylinux Compatibility

Current configuration uses manylinux: off in CI, building on the runner's native environment. For PyPI distribution, manylinux2014 (glibc 2.17) provides broad compatibility including:

  • RHEL/CentOS 7+
  • Ubuntu 18.04+
  • Debian 10+

No changes needed for 3.13/3.14 support.

musl/Alpine Linux

Not currently supported. PyO3 supports musl but would require separate wheel builds. Out of scope for this change.

32-bit Platforms

PyO3 0.27 fixed 3.14-specific issues on 32-bit systems. mrrc does not officially support 32-bit platforms (not in CI matrix), but should work.

Python 3.10 EOL Planning

Python 3.10 reaches EOL October 2026. Consider dropping 3.10 support in a future release (v0.8 or v1.0) to maintain a 4-version support window.

Testing Checklist

Before merging:

  • [ ] Build wheels locally for 3.10, 3.11, 3.12, 3.13, 3.14
  • [ ] Run full test suite on each version
  • [ ] Run benchmarks on 3.12, 3.13, 3.14 (compare performance)
  • [ ] Verify CI passes on all platforms
  • [ ] Test wheel installation from built artifacts
  • [ ] Update CHANGELOG with version changes

Timeline

Task Target
Implement changes 2026-02
Merge to main 2026-02
Release v0.7.0 with new version support 2026-02

References