Root cause behind the "pin the endpoint" gotcha and the trapping-wrapper
pattern: a gen_server had two lifetime authorities — its refs (last one
dropped → inbox closes → exit) and, when supervised, its supervisor. OTP has
one: a process lives until it stops, is shut down, or is killed; a pid is an
address. Root exit now shutting down every forest root removes the reason the
ref-governed idiom existed (a forgotten server no longer hangs the run), so
adopt the one rule:
- The server/machine loop holds one inbox sender for its life; the inbox
never closes. GenServerRef / GenStatemRef are addresses. Explicit close is
`shutdown()`; a forgotten one is swept at root exit.
- `NamedGenServerBuilder::run()` / `gen_statem::run_named(name, m)` run the
loop inline as the current actor: a server is a direct ChildSpec child,
gets the supervisor's shutdown as handle_shutdown / a shutdown row, re-binds
its name on restart, and is addressed by name. The wrapper in
examples/graceful_shutdown.rs is gone.
- gen_statem gains GenStatemName + whereis_machine/send/call/shutdown by name
(parity with gen_server); the macro gets `Sm::new`.
- Root-exit sweep records `Event::RootSweep { target, trapping }` under
smarm-trace ("root_sweep shutdown|stopped"): unsupervised leftovers are
visible rather than silently owned-by-refs.
- Named start() name-clash path stops the spawned actor instead of relying
on ref drop.
Tests: tests/gen_server_lifetime.rs, tests/gen_statem_lifetime.rs,
tests/root_sweep_trace.rs (feature-gated); three existing tests that used
drop-closes-inbox now use shutdown(). Docs/README/ROADMAP/Deep Dive updated.
Stack takes an explicit (reserve, guard) shape, both page-rounded and
stored; usable_base derives from the stored guard. Guard default raised
4 KiB -> 64 KiB (DEFAULT_STACK_GUARD): probestack makes one page enough
for Rust frames, but an unprobed C frame can leap a page in one sub rsp
— the motivating SQLite segfault. Reserve default stays 64 KiB
(DEFAULT_STACK_RESERVE); ACTOR_STACK_SIZE retired.
Config::{stack_reserve, stack_guard} thread the runtime defaults into
RuntimeInner pre-rounded. All acquisition/recycling now goes through
acquire_stack/recycle_stack carrying the pool rule: only default-shaped
stacks are pooled (pooled ⇒ default-shaped by induction); custom shapes
mmap fresh and munmap at death. Pool lock still dropped before any mmap.
No public spawn API change (SpawnOpts is the next commit).
Tests: shape rounding + accessors, wide-guard faults at both ends
(subprocess), Config::stack_reserve permits >64 KiB recursion that
previously could only segfault.
The profile was captured against the spin-enabled build. With the RFC 004
spinning experiment excised from master, the ~12% hot-path futex_wake it
attributed to the spinning submit-rule no longer exists (idle wait is back to
thread::sleep). Add a provenance note, mark the futex_wake row/finding as
excised spin machinery, and drop the now-moot 'gate the submit wake' lead.
Spin-independent findings (shims ~1%, schedule_loop + run-queue ~33%) unchanged.
- Replace v0.3 content throughout; bump version label to v0.8
- New SVG: Krebs-cycle scheduler loop (6 stations, actor handoff as
energy exchange, finalize leaving the cycle)
- New SVG: gen_server dual-plane (model vs implementation mapping)
- New SVG: slot state machine with packed word, park-epoch and all
transitions (loom theorems annotated)
- Updated SVG: module map (22 modules, 4 layers incl. slot_state,
run_queue, raw_mutex, sync_shim, monitor, link, registry, trace)
- Updated SVG: dep graph (runtime hub, OTP layer on public surface)
- New sections: Slot State & Park-Epoch, Run Queue variants,
GenServer, OTP (monitors/links/supervisors/registry)
- Updated: init (slab allocation, counter-based termination), spawn
(closure in slot AtomicPtr, stack pool, live_actors ordering),
preemption (stop sentinel + StopSentinel/Outcome::Stopped),
IO (epoch-matched completions, fd-leak fix), gotchas (lost-wakeup
and global-mutex flipped to green; 4 new cards)
- Yield-sources table grown to 9 rows (select, recv_timeout,
call, request_stop)
- Fix: swap local css2.css font ref for Google Fonts CDN
Claude (sandbox)