Split the monolithic `spawn._spawn` into a slim
"core" + per-backend submodules so a future
`._subint` backend (per issue #379) can drop in
without piling more onto `_spawn.py`.
`._spawn` retains the cross-backend supervisor
machinery: `SpawnMethodKey`, `_methods` registry,
`_spawn_method`/`_ctx` state, `try_set_start_method()`,
the `new_proc()` dispatcher, and the shared helpers
`exhaust_portal()`, `cancel_on_completion()`,
`hard_kill()`, `soft_kill()`, `proc_waiter()`.
Deats,
- mv `trio_proc()` → new `spawn._trio`
- mv `mp_proc()` → new `spawn._mp`, reads `_ctx` and
`_spawn_method` via `from . import _spawn` for
late binding bc both get mutated by
`try_set_start_method()`
- `_methods` wires up the new submods via late
bottom-of-module imports to side-step circular
dep (both backend mods pull shared helpers from
`._spawn`)
- prune now-unused imports from `_spawn.py` — `sys`,
`is_root_process`, `current_actor`,
`is_main_process`, `_mp_main`, `ActorFailure`,
`pretty_struct`, `_pformat`
Also,
- `_testing.pytest.pytest_generate_tests()` now
drives the valid-backend set from
`typing.get_args(SpawnMethodKey)` so adding a
new backend (e.g. `'subint'`) doesn't require
touching the harness
- refresh `spawn/__init__.py` docstring for the
new layout
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Gud Boi
d7ca68cf61