feat: stress tests, expanded benchmarks, and research extension
Cycle 2 of the competitor analysis improvement loop.
Research additions:
- Kameo: async on tokio, dual bounded/unbounded mailbox (default 64),
Erlang-style supervision links, vtable dispatch
- Actix: custom Vyukov lock-free MPSC queue (why it's fastest),
256-message assertion guard (validates our budget), Context-as-Future
New stress tests (6):
- Message ordering preserved under small budget (budget=8)
- Multi-threaded: 50 senders × 100 msgs to one receiver (4 threads)
- Concurrent spawn+send of 200 actors (4 threads)
- 50-level chain spawning across 2 workers
- Panic isolation: 10 panicking + 10 healthy actors (4 threads)
- Sustained throughput: 10 batches of 100 msgs with interleaved ticks
New benchmark groups:
- msg_size: throughput and send_latency by message size (8B-4KB)
- contention: fanin (1-100 senders), cross_worker (1-4 threads)
All 57 tests pass (51 runtime_api + 5 transport + 1 doctest).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>