lu-table-insert-hot — table.insert vs t[i]=
Claim
Measured on this machine: primary hot case table_insert ratio before/after ~4.74× (faster after). Default severity stays off. Do not escalate to error from this fill alone.
How measured
- Harness:
packages/luaperf/examples/bench/evidence_lu001.lua - Protocol: warm=3; median of 9 rounds; GC/collect where applicable
- Raw lines:
lu-table-insert-hot.jsonl
Runtime (this evidence file)
| Field | Value |
|---|---|
| When | 2026-10-22 Asia/Shanghai (machine clock; JSONL ts is UTC) |
| Toolchain | Lua 5.4.7 |
Median after (index_assign) | 2.029000 ms (ops=200000, ratio=1.000000) |
Median before (table_insert) | 9.620000 ms (ops=200000, ratio=4.741252) |
Median after (hash_len_append) | 3.926000 ms (ops=200000, ratio=1.000000) |
Median before (table_insert_vs_len) | 9.620000 ms (ops=200000, ratio=2.450331) |
Median after (small_index) | 3.814000 ms (ops=100, ratio=1.000000) |
Median before (small_insert) | 13.184000 ms (ops=100, ratio=3.456738) |
| Primary ratio before/after | ~4.74× (table_insert) |
Direction and absolute ms are N/machine/opt-sensitive. Re-run the harness after toolchain or machine changes.
Lint mapping
luaperf-lint lu-table-insert-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.