New pytest module `tests/spawn/test_subint_forkserver.py`
drives the forkserver primitives from inside a real
`trio.run()` in the parent — the runtime shape tractor will
actually use when we wire up a `subint_forkserver` spawn
backend proper. Complements the standalone no-trio-in-parent
`ai/conc-anal/subint_fork_from_main_thread_smoketest.py`.
Deats,
- new test pkg `tests/spawn/` (+ empty `__init__.py`)
- two tests, both `@pytest.mark.timeout(30, method='thread')`
for the GIL-hostage safety reason doc'd in
`ai/conc-anal/subint_sigint_starvation_issue.md`:
- `test_fork_from_worker_thread_via_trio` — parent-side
plumbing baseline. `trio.run()` off-loads forkserver
prims via `trio.to_thread.run_sync()` + asserts the
child reaps cleanly
- `test_fork_and_run_trio_in_child` — end-to-end: forked
child calls `run_subint_in_worker_thread()` with a
bootstrap str that does `trio.run()` in a fresh subint
- both tests wrap the inner `trio.run()` in a
`dump_on_hang()` for post-mortem if the outer
`pytest-timeout` fires
- intentionally NOT using `--spawn-backend` — the tests
drive the primitives directly rather than going through
tractor's spawn-method registry (which the forkserver
isn't plugged into yet)
Also, rename `run_trio_in_subint()` →
`run_subint_in_worker_thread()` for naming consistency with
the sibling `fork_from_worker_thread()`. The action is really
"host a subint on a worker thread", not specifically "run
trio" — trio just happens to be the typical payload.
Propagate the rename to the smoketest.
Further, add a "TODO — cleanup gated on msgspec PEP 684
support" section to the `_subint_forkserver` module
docstring: flags the dedicated-`threading.Thread` design as
potentially-revisable once isolated-mode subints are viable
in tractor. Cross-refs `msgspec#563` + `tractor#379` and
points at an audit-plan conc-anal doc we'll add next.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
Gud Boi