Support Python 3.14

[NeilGirdhar]

Description

Last year, Ray was just over 4 months late supporting Python 3.13. Now that release candidates for Python 3.14 are out, it might be worth it to start testing Ray with Python 3.14.

Use case

The biggest changes to the implementation include template strings (PEP 750), deferred evaluation of annotations (PEP 649), and a new type of interpreter that uses tail calls.

[NeilGirdhar]

@jjyao Python 3.14 is set to release in two weeks and there are still no PRs for this issue. Can this be bumped to P0 please?

[jjyao]

@aslonnie will decide the priority based on bandwidth etc.

[NeilGirdhar]

Just as an FYI: much of the scientific Python ecosystem began preparing for 3.14 months ago and already publishes wheels that install cleanly on 3.14—including NumPy, SciPy, JAX, and others. By contrast, Ray doesn’t appear to have started 3.14 work yet, which means we’ll likely be waiting several more months before support is available.

Python 3.14 is due to be released on Tuesday.

[aslonnie]

we need to first be able to build the ray core bits.