Add spawn_restartable(actor, factory, max_restarts) to Runtime and Ctx.
On panic, the actor is recreated using the factory with fresh state and
cleared mailbox. After max_restarts exhausted, permanently poisoned.
AnyActor::try_restart() trait method with backward-compatible default.
Factory stored as Arc<dyn Fn() -> A + Send + Sync> — safe to read after
catch_unwind since factory fields are never touched by handle_any.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add optional bounded mailboxes to prevent unbounded memory growth.
MailboxOverflow enum: DropNewest (discard incoming) or DropOldest
(evict oldest to make room). Default capacity=0 preserves unbounded
behavior for full backward compatibility.
messages_dropped counter added to WorkerStats for observability.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Replace blind round-robin placement with load-aware strategy that reads
per-worker stats (actor count + mailbox depth) and biases toward lighter
workers. Falls back to round-robin when stats are equal (initial burst).
Deep research on work stealing across Tokio (steal-half, LIFO slot),
Go (M:N scheduler), BEAM (proactive migration), and ForkJoinPool.
Full actor migration is feasible but deferred due to message-loss window.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
shutdown() now wakes all parked workers immediately for fast exit.
5 new tests from competitor bug patterns: ractor #310 (destructive
snapshots), kameo #185 (startup delivery), actix #515 (mailbox bypass),
plus stats-under-load and shutdown-wakes-parked validation.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Replace thread::sleep with thread::park_timeout in worker backoff loop.
Workers register their thread handle via OnceLock<Thread> on startup.
When send_to or spawn routes work to a worker, Thread::unpark() wakes
it instantly instead of waiting for the sleep timer to expire.
Inspired by tokio's parker state machine and Linux NO_HZ adaptive ticks.
Implementation:
- Runtime stores Vec<OnceLock<Thread>> for worker thread handles
- Workers call OnceLock::set(thread::current()) on startup
- Runtime::send_any, spawn_any, and WorkerContext cross-worker sends
call notify_worker() → Thread::unpark() on the target worker
- TickContext carries worker_threads reference for cross-worker notification
- Zero new dependencies (std::sync::OnceLock + std:🧵:park_timeout)
Benefits:
- Parked workers wake instantly when work arrives (vs up to 1ms sleep delay)
- No overhead on hot path — unpark() is no-op if thread isn't parked
- Single-threaded tick() mode unaffected (OnceLock never set)
All 58 tests pass (52 runtime_api + 5 transport + 1 doctest).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Research across ractor, tokio, Erlang/OTP BEAM, Linux CFS, and libuv
revealed that tick_all drained the entire mailbox per actor per tick,
allowing one hot actor to starve all others on the same worker.
- Add `actor_message_budget` to RuntimeConfig (default: 64 msgs/actor/tick)
- Modify tick_all to break after budget messages, yielding to next actor
- budget=0 restores unlimited (backward compatible) behavior
- 3 new fairness tests validating hot-cold actor scenarios
- New fairness benchmark group (cold_latency_under_pressure, throughput_by_budget)
- Fix RuntimeConfig struct literals across workspace crates
Inspired by BEAM's 4000-reduction budget and tokio's 128-op cooperative budget.
All 45 tests pass (42 original + 3 new).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Adds some basic benchmarking, stress tests. They still need to be properly examined to ensure they are testing the correct properties, but fit for "good enough". Implements the HybridChannel type, which features a channel buffer that can withstand overflows. It does so by providing a dequeue behind a mutex. Without overflow, will push messages into the lock free ArrayQueue implemented by crossbeam_queue; when that buffer fills, will use the locking portion provided by the Mutex<VecDequeue>.
In the future we can even further optimize this, perhaps with some linked list implementations of lock-free channels, but, like the benchmarks, this fits the "good enough" bar for now.
