Cycle 16: Registry Benchmarks for Named Actors, Groups, Monitors, and Ask — Development History

Commit: 0ef6df9 · 2 files · 130 insertions, 1 deletion

Motivation

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.

Benchmark Results

Benchmark	Time	Analysis
`named_spawn_lookup`	~2.4 µs	vs bare spawn 1.9 µs → +0.5 µs overhead for name registration
`where_is_100_names`	~9.0 µs	Includes setup overhead; per-lookup cost is negligible
`group_publish/10`	~4.8 µs	O(N) message cloning
`group_publish/50`	~15.5 µs	Linear scaling confirmed
`group_publish/100`	~60 µs	Linear with O(N) clones
`monitor_setup`	~13.4 µs	monitor + stop + cleanup full cycle
`ask_roundtrip`	~4.5 µs	vs manual roundtrip 3.0 µs → +1.5 µs for inbox creation

Analysis

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.
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).
Monitor setup: 13.4 µs covers the full lifecycle (monitor → stop → cleanup → Down delivery). The monitoring machinery adds minimal per-message overhead.
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.

Implementation

5 new criterion benchmark functions added to benches/runtime_benchmarks.rs in a registry group:

named_spawn_lookup — spawn_named + where_is roundtrip
where_is_100_names — lookup in 100-name registry
group_publish/{10,50,100} — broadcast to N group members
monitor_setup — monitor + stop + Down delivery cycle
ask_roundtrip — ask + recv_ticking response

Key files modified: benches/runtime_benchmarks.rs

Design Decisions

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.
Parameterized group publish — three group sizes (10, 50, 100) to verify linear scaling and catch any unexpected superlinear behavior.
No optimization undertaken — all operations are efficient enough. The benchmark results serve as baselines for future changes.

Tests Added

No new tests (benchmarks only). Test count remains at 127.

Result

All benchmarks run cleanly
127 tests pass, zero warnings
All registry operations confirmed efficient for production use
Named lookup: <1 µs overhead over bare spawn
Ask: ~50% overhead over manual inbox pattern (acceptable for convenience)
Group publish: linear O(N) as expected

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