gp-string-plus-hot — string += vs strings.Builder
Claim
Measured on this machine: primary hot case string_plus ratio before/after ~1481.22× (faster after). Default severity stays off. Do not escalate to error from this fill alone — ratio is strong but policy/default and G3 OK-idiom history keep severity unchanged.
How measured
- Harness:
packages/goperf/examples/bench/evidence_gp.go - Protocol: warm=3; median of 9 rounds; GC/collect where applicable
- Raw lines:
gp-string-plus-hot.jsonl
Runtime (this evidence file)
| Field | Value |
|---|---|
| When | 2026-10-23 Asia/Shanghai (machine clock; JSONL ts is UTC) |
| Toolchain | go1.27.3 |
Median after (strings_builder) | 0.217000 ms (ops=50000, ratio=1.000000) |
Median before (string_plus) | 321.424750 ms (ops=50000, ratio=1481.220046) |
Median after (small_builder) | 0.000334 ms (ops=100, ratio=1.000000) |
Median before (small_string_plus) | 0.001667 ms (ops=100, ratio=4.991018) |
| Primary ratio before/after | ~1481.22× (string_plus) |
Direction and absolute ms are N/machine/opt-sensitive. Re-run the harness after toolchain or machine changes.
Lint mapping
goperf-lint gp-string-plus-hot default stays off. Escalate recommended: no.
Limits
- Microbench; not an app profile.
- Small-N rows may sit near timer noise; prefer hot (non-small) cases for ratio claims.
- I/O rules (print/echo/puts/writeln) discard to
/dev/null— env-dependent.