Two cleanup tweaks in `_main_thread_forkserver`:
Doc, "what survives the fork?" section — expand the
"non-calling threads are gone in the child" claim with
the precise execution-vs-memory split that reconciles
this module's prior framing with trio's (canonical
[python-trio/trio#1614][trio-1614]) "leaked stacks"
framing:
- execution-side: only the calling thread runs
post-fork; all others never execute another
instruction.
- memory-side: those non-running threads' stacks +
per-thread heap structures are still COW-inherited
as orphaned bytes — what trio means by "leaked".
Same POSIX reality, opposite sides; the table is
extended to a 4-col `parent | child (executing) |
child (memory)` layout to make both views explicit.
Also blank-line-padded the bulleted hazard classes
for cleaner markdown rendering.
[trio-1614]: https://github.com/python-trio/trio/issues/1614
Code, `_close_inherited_fds()` log noise — split the
catch-all `except OSError` into:
- `EBADF` — benign race where the dirfd that
`os.listdir('/proc/self/fd')` itself opened ends up
in `candidates`, then auto-closes before the loop
reaches it. Demote to `log.debug()` + `continue`;
prior `log.exception` drowned the post-fork log
channel with stack traces every spawn.
- other errnos (EIO / EPERM / EINTR / ...) keep the
loud `log.exception` surface — those ARE genuinely
unexpected.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit 8c730193f9)
The `subint_forkserver` name was always aspirational —
today's impl forks from a regular main-interp worker
thread and the child runs trio on its own main interp;
NO subinterp anywhere in parent or child. Splitting the
backend into two clearly-named variants drops the lie:
- **variant 1** — `main_thread_forkserver` (the working
impl). New `SpawnMethodKey` literal + `_methods`
dispatch entry + `_runtime.Actor._from_parent()`
match-arm. The spawn-coro `subint_forkserver_proc`
moves to `_main_thread_forkserver` and is renamed
`main_thread_forkserver_proc()`.
- **variant 2** — `subint_forkserver` (future, reserved).
Module shrinks to a placeholder describing the
variant-2 design (subint-isolated child runtime, gated
on jcrist/msgspec#1026 + PEP 684). Today the legacy
`'subint_forkserver'` key aliases to
`main_thread_forkserver_proc` so existing
`--spawn-backend=subint_forkserver` invocations keep
working; flipped to a `NotImplementedError` stub in a
follow-up.
Deats,
- `Actor._from_parent()` spawn-method gate now accepts
both `'main_thread_forkserver'` and
`'subint_forkserver'` (both go through the
IPC-`SpawnSpec` path).
- the variant-1 spawn-coro stamps its own `SpawnSpec` /
log lines with `spawn_method='main_thread_forkserver'`
so subactor renders reflect the actual mechanism.
- docstring reorg: trio×fork hazard breakdown, POSIX
fork-survival semantics, in-process-vs-stdlib
forkserver design notes, and the TODO/cleanup section
all move from `_subint_forkserver` to
`_main_thread_forkserver` (lives with the working
code). `_subint_forkserver` keeps a tight forward-
looking doc that motivates the reserved key.
- `run_subint_in_worker_thread()` stays in
`_subint_forkserver` as the companion primitive — it's
the subint counterpart to `fork_from_worker_thread()`
and will plug into the future variant-2 spawn-coro.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit 57dae0e4a6)
Move the truly-generic main-interp-worker-thread fork primitives
(`fork_from_worker_thread`, `_close_inherited_fds`, `_ForkedProc`,
`wait_child`, `_format_child_exit`) out of `_subint_forkserver.py` into
a sibling `_main_thread_forkserver.py` module so the primitive layer is
honestly named — none of these helpers touch a subint, they just fork
from a main-interp worker thread.
`_subint_forkserver.py` keeps its public surface intact via re-export so
any existing `from tractor.spawn._subint_forkserver import ...` callsite
still resolves.
Net: zero behavior change, preps the way for the upcoming spawn-method
key split where `main_thread_forkserver` ships as the working backend
and `subint_forkserver` becomes reserved for the future
subint-isolated-child variant (gated on jcrist/msgspec#1026).
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
(cherry picked from commit 99dade0fb3)
Gud Boi