doc: record rejected trace_agent v04 buffer-reuse optimization #1738
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Attempted buffer reuse optimization in trace_agent v04 serialization. While it reduced total allocated memory by 67.6%, it caused a 6.6% time regression, failing the review process. Target: lading_payload/src/trace_agent/v04.rs::V04::to_bytes Technique: buffer-reuse Status: REJECTED Measurements: - Time: +6.6% (13.6 ms -> 14.5 ms) ❌ - Total allocated: -67.6% (32.55 MiB -> 10.56 MiB) ✓ - Allocations: -1.2% (18,141 -> 17,921) Review verdict: REJECTED by Skeptic persona Reason: Time regression violates performance improvement requirement Lesson: Buffer reuse patterns that work for simple serializers don't necessarily work for msgpack serialization with complex nested structures. The binary search sizing loop combined with buffer reuse may cause cache or performance issues. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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Summary
Documents a rejected optimization attempt for educational purposes.
Attempted buffer reuse optimization in trace_agent v04 serialization. While it reduced total allocated memory by 67.6%, it caused a 6.6% time regression, failing the 5-persona review process.
Target
lading_payload/src/trace_agent/v04.rs::V04::to_bytesMeasurements
Before (Baseline)
After (Optimized)
Review Verdict: REJECTED
Rejected by Skeptic persona due to time regression.
While the optimization achieved a dramatic 67.6% reduction in total allocated memory, it caused an unacceptable 6.6% time regression (13.6ms → 14.5ms).
Lesson Learned
Buffer reuse patterns that work excellently for simple text-based serializers (syslog, dogstatsd, datadog_logs) don't necessarily translate to msgpack serialization with complex nested structures.
The combination of:
.clear()...created an unexpected performance regression despite dramatically reducing allocations.
This is valuable institutional knowledge - we now know NOT to apply this pattern to trace_agent v04, saving future optimization efforts.
Changes
This PR only updates documentation databases:
.claude/skills/lading-optimize-hunt/assets/db.yaml.claude/skills/lading-optimize-hunt/assets/db/trace-agent-v04-buffer-reuse.yaml.claude/skills/lading-optimize-review/assets/db.yaml.claude/skills/lading-optimize-review/assets/db/opt-trace-agent-v04-buffer-reuse.yamlNo production code changes - the rejected optimization was reverted.
🤖 Generated with Claude Code