60 lines
3.1 KiB
Markdown
60 lines
3.1 KiB
Markdown
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# Cycle 16: Registry Benchmarks for Named Actors, Groups, Monitors, and Ask — Development History
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> Commit: `0ef6df9` · 2 files · 130 insertions, 1 deletion
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---
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## Motivation
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Cycles 12–15 added four new features (named registry, monitoring, groups, ask pattern) without performance measurement. Before building more features on top of these primitives, it was important to quantify their overhead and ensure they're efficient enough for production use.
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## Benchmark Results
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| Benchmark | Time | Analysis |
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|-----------|------|----------|
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| `named_spawn_lookup` | ~2.4 µs | vs bare spawn 1.9 µs → **+0.5 µs** overhead for name registration |
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| `where_is_100_names` | ~9.0 µs | Includes setup overhead; per-lookup cost is negligible |
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| `group_publish/10` | ~4.8 µs | O(N) message cloning |
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| `group_publish/50` | ~15.5 µs | Linear scaling confirmed |
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| `group_publish/100` | ~60 µs | Linear with O(N) clones |
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| `monitor_setup` | ~13.4 µs | monitor + stop + cleanup full cycle |
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| `ask_roundtrip` | ~4.5 µs | vs manual roundtrip 3.0 µs → **+1.5 µs** for inbox creation |
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### Analysis
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- **Named lookup**: +0.5 µs over bare spawn — the `RwLock<HashMap>` insert is fast. Acceptable for a feature used at spawn time, not on the hot path.
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- **Group publish**: scales linearly with group size, as expected for O(N) message cloning. No optimization needed — the bottleneck is inherent (must clone and deliver N messages).
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- **Monitor setup**: 13.4 µs covers the full lifecycle (monitor → stop → cleanup → Down delivery). The monitoring machinery adds minimal per-message overhead.
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- **Ask roundtrip**: +1.5 µs over manual inbox pattern (4.5 µs vs 3.0 µs). The overhead is inbox creation. Acceptable for a convenience pattern — users who need maximum throughput can use the manual pattern.
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## Implementation
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5 new criterion benchmark functions added to `benches/runtime_benchmarks.rs` in a `registry` group:
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- `named_spawn_lookup` — spawn_named + where_is roundtrip
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- `where_is_100_names` — lookup in 100-name registry
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- `group_publish/{10,50,100}` — broadcast to N group members
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- `monitor_setup` — monitor + stop + Down delivery cycle
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- `ask_roundtrip` — ask + recv_ticking response
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**Key files modified:** `benches/runtime_benchmarks.rs`
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## Design Decisions
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- **Full-cycle benchmarks** — each benchmark measures the complete operation (not just the fast path). For example, `monitor_setup` includes stop and cleanup, not just the monitor call, because that's the real-world cost.
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- **Parameterized group publish** — three group sizes (10, 50, 100) to verify linear scaling and catch any unexpected superlinear behavior.
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- **No optimization undertaken** — all operations are efficient enough. The benchmark results serve as baselines for future changes.
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## Tests Added
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No new tests (benchmarks only). Test count remains at 127.
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## Result
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- All benchmarks run cleanly
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- 127 tests pass, zero warnings
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- All registry operations confirmed efficient for production use
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- Named lookup: <1 µs overhead over bare spawn
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- Ask: ~50% overhead over manual inbox pattern (acceptable for convenience)
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- Group publish: linear O(N) as expected
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