The #470 boot-latency example hard-coded spawning each `worker_<i>`
subactor concurrently from a bg `trio.Task` (so each child's cold
`import tractor` overlaps). Add a `main()` `spawn_subs_in_bg_tasks`
flag so the serial-spawn path can be demo'd/compared too: flip it
`False` to `start_actor()` each sub inline in the loop before
handing the ready `Portal` to the bg task.
Deats,
- factor an `open_ep(ptl, i)` helper out of `spawn_and_open_ep()` -
just the `Portal.open_context()` + `wait_for_result()` half, now
that the spawn step is caller-optional.
- `spawn_and_open_ep()` grows a `maybe_ptl: Portal|None = None`
param: spawn the subactor itself when unset (bg-task path), OW
reuse the pre-spawned one (serial path).
- move the "overlap cold imports" rationale comment onto the new
`main()` param where the toggle now lives.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code
`run_in_actor()` is slated to become a hilevel wrapper
(`runtime/_supervise.py` "TODO: DEPRECATE THIS"), so the showcase
`we_are_processes.py` shouldn't lead with it. Move it to the modern
API: each `worker_<i>` subactor runs a `@tractor.context`
`endpoint()` that `started()`-hands its name + pid back over
`Portal.open_context()` and parks; the root sleeps then raises on
purpose so the runtime reaps the whole tree (zero zombies).
The subs spawn concurrently from bg `trio.Task`s so each child's
cold `import tractor` (~0.4s, see #470) overlaps instead of
stacking; a comment flags the coming `main_thread_forkserver`
backend (#463) which'll make serial spawns cheap enough to just
loop.
Match the landing prose to the snippet — name the `Context` +
`started()` handshake it now leads with.
Also, document `--watch examples` on the `sphinx-autobuild` cmds so
edits to `literalinclude`-d example scripts (which live outside
`docs/`) live-reload too.
(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code