logos-delivery/docs/analysis/bench_baseline.md

Message-path benchmark — Phase 1 baseline

Baseline capture on the current branch before Phases 2/3, produced by apps/benchmarks/message_path_bench.nim (see plan_phase1_bench.md). Re-run after each phase and diff against these numbers.

Environment

Item	Value
Commit (harness)	cf8502eb4975ae6bc8a5667a5d179cd154e8e1d1
Branch	experimental/chore-nocopy-e2e-perf-harness
Machine	Apple M4
OS	macOS 26.5 (arm64)
Nim	2.2.4, --mm:refc
Build	-d:msgPathCounters -d:chronicles_log_level=ERROR, --passL:librln_v2.0.2.a
Run	nimble benchMessagePath (or ./build/message_path_bench)
Workload	seed 42, payload mix 10/50/150 kB @ 25/50/25 %, N=1000 + 100 warmup

Results (CSV)

scenario,msgs,payload_profile,wall_ms,msg_per_s,ns_per_msg_p50,ns_per_msg_p99,decodes_per_msg,hashes_per_msg,hashed_MB,decoded_MB,occupied_mem_delta_MB,gc_collections
micro_run1,1000,10/50/150kB@25/50/25,828.591,1206.9,641375,1925042,2.000,2.000,130.00,130.11,1.54,7
micro_run2,1000,10/50/150kB@25/50/25,795.166,1257.6,619167,1810625,2.000,2.000,130.00,130.11,1.51,8
macro,1000,10/50/150kB@25/50/25,4367.314,229.0,3510750,10701375,6.000,5.000,325.00,390.33,141.58,10

Scenario	msg/s	decodes/msg	hashes/msg	decoded_MB	hashed_MB	occ_mem_delta_MB
micro run1	1206.9	2.000	2.000	130.11	130.00	1.54
micro run2	1257.6	2.000	2.000	130.11	130.00	1.51
macro	229.0	6.000	5.000	390.33	325.00	141.58

Micro determinism: run1=1206.9 msg/s, run2=1257.6 msg/s → variance 4.03 % (< 5 % target; two earlier back-to-back runs were 1.90 % and 3.12 %). The decode/hash counts are byte-exact reproducible across every run.

Interpretation vs. the analysis

Decode / hash counts validate async_copy_analysis.md.

The counter is a single process-global (both in-process nodes share it), so the macro per-message numbers are the aggregate of publisher (node A) + receiver (node B). Breakdown of the macro 6 decodes / 5 hashes per message:

Counter	Node A (publish)	Node B (receive)	Total
WakuMessage.decode	1 (onSend observer)	4 (ordered validator, onRecv, onValidated, subscribe topicHandler)	6
computeMessageHash	2 (publish :686, onSend→logMessageInfo)	3 (onValidated→logMessageInfo, archive, store-sync)	5

• The inbound-decode claim (≥4 decodes on a relayed message) is confirmed: node B alone decodes the same proto bytes 4× (waku_relay/protocol.nim validator :543, onRecv :271, onValidated :326, topicHandler :603).
• The micro scenario isolates the non-observer path and shows the 2 decodes / 2 hashes it exercises (validator + topicHandler decode; archive + store-sync hash) — the observers only fire under real libp2p dispatch, which the macro scenario adds.

Caveats

1. Log level elides some hash sites. Built at chronicles_log_level=ERROR, computeMessageHash calls that appear only as disabled log arguments are not evaluated (chronicles skips disabled-sink args) — notably the node.publish notice at waku_node/relay.nim:148. Sites bound to a let (archive :101, store-sync :78, logMessageInfo :217, publish :686) run regardless of level and are the ones counted here.
2. Filter not mounted. Per the plan, node B has archive + store-sync but not filter. The analysis's "4–6 hashes" upper end assumes an active filter (waku_filter_v2 adds ~2 more receiver-side computeMessageHash passes, :195 + :246). With filter mounted the receiver-side hash count would rise from 3 toward the analysis's upper bound.
3. occupied_mem_delta is a coarse getOccupiedMem() before/after delta on the refc heap, not a per-message allocation trace; use it for order-of- magnitude trend, not exact bytes. decoded_MB / hashed_MB (exact byte totals fed to decode/hash) are the reliable volume metrics.

Acceptance gate (Phase 1)

#	Criterion	Verdict
1	Representative tests green (production untouched except no-op templates)	PASS — tests/waku_core/test_message_digest 5/5, tests/waku_relay/test_protocol 20/20
2	Production build without -d:msgPathCounters compiles (templates vanish)	PASS — nim check apps/wakunode2 clean; relay test built without the define
3	Two consecutive micro runs < 5 % msg/s variance	PASS — 4.03 % (and 1.90 % / 3.12 % on earlier runs)
4	Macro decodes_per_msg ≥ 4 and hashes_per_msg in 4–6	PASS — decodes 6.0, hashes 5.0 (process aggregate; receiver-side decodes = 4)
5	This baseline doc committed	PASS

---

Phase 2 checkpoint — WakuMessage as ref object

Re-run of the same harness after Phase 2 (WakuMessage value object → ref object), same machine/toolchain, same workload (seed 42, 10/50/150 kB @ 25/50/25 %, N=1000 + 100 warmup), same build defines (-d:msgPathCounters -d:chronicles_log_level=ERROR, --passL:librln_v2.0.2.a --passL:-lm), --mm:refc.

Results (CSV)

scenario,msgs,payload_profile,wall_ms,msg_per_s,ns_per_msg_p50,ns_per_msg_p99,decodes_per_msg,hashes_per_msg,hashed_MB,decoded_MB,occupied_mem_delta_MB,gc_collections
micro_run1,1000,10/50/150kB@25/50/25,809.283,1235.7,624250,1941750,2.000,2.000,130.00,130.11,5.25,7
micro_run2,1000,10/50/150kB@25/50/25,798.488,1252.4,615750,1906167,2.000,2.000,130.00,130.11,6.46,8
macro,1000,10/50/150kB@25/50/25,4306.885,232.2,3485125,10544000,6.000,5.000,325.00,390.33,140.74,10

(second run: micro 1232.1 / 1278.1, variance 3.60 %; macro 230.2 msg/s, occ_mem_Δ 140.58 MB — stable.)

Phase 1 baseline vs Phase 2

Scenario	Metric	Phase 1 baseline	Phase 2	Δ
micro	msg/s	1206.9 / 1257.6	1235.7 / 1252.4	~flat (within variance)
micro	decodes/msg	2.000	2.000	unchanged
micro	hashes/msg	2.000	2.000	unchanged
micro	occ_mem_Δ MB	1.51–1.54	5.25–6.46	up (retention-noise, see below)
macro	msg/s	229.0	232.2 / 230.2	+1 %
macro	decodes/msg	6.000	6.000	unchanged
macro	hashes/msg	5.000	5.000	unchanged
macro	hashed_MB / decoded_MB	325.00 / 390.33	325.00 / 390.33	byte-exact unchanged
macro	occ_mem_Δ MB	141.58	140.74 / 140.58	~flat (−0.6 %)
macro	gc_collections	10	10	unchanged

Interpretation — why occupied-mem delta is flat (and that is expected)

The refactor removes transient deep copies — async-closure env captures in node dispatch (subscription_manager handlers, 6–7 per message), Result/Option bind-outs, and the valueOr binds on the decode path. It does not change what is retained.

occupied_mem_delta is getOccupiedMem() after − before (with a GC_fullCollect() only before the run). It is therefore a retained-memory metric, and the macro figure is dominated by the archive SortedSet[Index, WakuMessage] holding all 1000 messages. Those payload bytes are retained identically under value and ref semantics (value: copied into the set node; ref: one heap message the set points at) — so the delta is flat by construction.

Under --mm:refc the eliminated transient copies are freed deterministically by refcount as each async env / Result temporary leaves scope; they never accumulate, so neither getOccupiedMem()-delta nor gc_collections (unchanged at 10) can observe their removal. Quantifying the transient-copy volume would require a cumulative bytes-allocated counter or a peak-RSS probe, which the Phase 1 harness does not expose — a harness gap, not a missing win.

The primary correctness gate is met: decode and hash counters are byte-exact identical to baseline (micro 2/2, macro 6/5; hashed_MB/decoded_MB identical to the byte), confirming the ref change introduced no extra decode/hash passes, and throughput is equal-to-slightly-better.

Residual-deep-copy investigation (plan acceptance item 3): swept for the two prime suspects and found neither — no value-type WakuMessage field remains (the type is now a ref, so every container/field that held a WakuMessage, incl. SortedSet[Index, WakuMessage], MessagePush.wakuMessage, WakuMessageKeyValue.message, holds a pointer); the known var-parameter copy site (relay publish) was converted to ensureTimestampSet. No leftover force-copy path exists.

Acceptance gate (Phase 2)

#	Criterion	Verdict
1	Representative tests green; ASAN clean	PASS (tests) — see final report for suite list; ASAN best-effort noted there
2	Mutation-site classification produced	PASS — docs/analysis/phase2_mutation_audit.md
3	Alloc volume down ≥ 40 %, decode/hash unchanged	PARTIAL — decode/hash byte-exact unchanged (PASS); alloc-volume drop not demonstrable via this harness's retained-memory metric under refc (technical reason above); no residual deep-copy bug found
4	detect_changes reviewed; committed (no push)	PASS (gitnexus skipped per environment; grep-based mutation sweep committed instead)