Free-threaded Python (3.14t) support#151
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Full-lane design change + a decision recording free-threading as a compatibility guarantee (runs on 3.14t, GIL off) rather than a parallelism redesign, and why 3.14t is the only target (deps ship cp314t wheels, no cp313t). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Local proof on 3.14t showed SQLAlchemy's Cython extensions re-enable the GIL (they ship cp314t wheels but don't declare Py_MOD_GIL_NOT_USED). Scope the guarantee to DISABLE_SQLALCHEMY_CEXT_RUNTIME=1 (SQLAlchemy's sanctioned switch); record a decision with a revisit trigger. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Adds a standalone `freethreaded` job that installs 3.14t, runs the full suite (--no-cov), and asserts sys._is_gil_enabled() is False so a dependency that silently re-enables the GIL fails the build. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Advertises the CI-proven 3.14t free-threaded compatibility on PyPI. Conservative first claim; bump to 3 - Stable after real-world soak. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
States what is guaranteed (runs on 3.14t, GIL off) and what is not (no extra in-process parallelism; the subscriber stays single-loop). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The suite's pytest step runs GIL-on (test tooling imports aiokafka at collection, which re-enables the GIL); only the standalone assertion step proves the outbox's runtime dependency graph keeps the GIL disabled. Word the docs/spec to reflect both facts instead of implying the suite runs GIL-off. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Benchmark gate✅ gate passed
Gated (fails the build): |
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Guarantees free-threaded (no-GIL) CPython 3.14t compatibility — a
compatibility guarantee, not a behavior change. No runtime/source change to the
package.
What lands
freethreadedCI job: installs 3.14t, runs the full suite(
--no-cov), and assertssys._is_gil_enabled() is Falsefor the outbox'sruntime dependency graph so a silent GIL re-enable turns the build red.
Programming Language :: Python :: Free Threading :: 2 - Betaclassifier.Notable finding baked into the design: SQLAlchemy's Cython extensions ship
cp314twheels but don't declare free-thread safety, so importing SQLAlchemyre-enables the GIL. The job sets
DISABLE_SQLALCHEMY_CEXT_RUNTIME=1(SQLAlchemy'sown switch); the docs tell users to do the same for a genuinely GIL-free process.
The suite itself runs GIL-on (test-only
aiokafkare-enables it at collection) —the docs state the two CI facts separately.
Design & rationale:
planning/changes/2026-07-18.01-free-threaded-support.mdDecisions:
planning/decisions/2026-07-18-free-threading-is-compat-only.md,planning/decisions/2026-07-18-sqlalchemy-cyext-disables-gil.mdFollow-up (repo admin): add
freethreadedto branch-protection required checks,as with the other
_checksjobs.🤖 Generated with Claude Code