Mihaela Mihaljevic
8e1415aa64
scripts/benchmark.sh generates a deterministic corpus, builds PureXML in release and a C driver against the SDK's libxml2, times parse, serialize, and XPath over the same bytes (best-of-N, internal timing, IO excluded), cross-checks the same XPath count on both sides, and prints the comparison. First honest baseline recorded in docs/benchmarks.md: parse ~30x, xpath ~36x, serialize ~5x slower than libxml2 on a 4.2 MB corpus; these are the numbers #139's optimization passes burn down. The SAX stage isolation is blocked on #142 (the public streaming surface is internal, found by this harness).
1.5 KiB
1.5 KiB
Benchmarks: PureXML vs libxml2 (#139)
bash scripts/benchmark.sh [items] [iterations] generates a deterministic
corpus (never vendored), builds PureXML in release and the C driver against
the macOS SDK's libxml2, runs both over the same bytes with internal timing
(best-of-N, IO excluded), and prints the comparison. Both drivers also
cross-check the same XPath count, so every benchmark run doubles as a
cross-implementation correctness check.
Baseline (first measurement)
20000 items, ~4.2 MB, best of 5, Apple Silicon (Studio), release builds:
| operation | PureXML | libxml2 | ratio |
|---|---|---|---|
| parse | 0.49 s | 0.016 s | ~30x |
| serialize | 0.059 s | 0.012 s | ~5x |
| xpath | 0.42 s | 0.012 s | ~36x |
These are the honest starting numbers the #139 optimization passes burn down; the table updates as passes land, never silently.
Known structure of the gap
- Parse and XPath dominate; serialize is closest.
- The scanner-vs-tree split needs the SAX stage, blocked on #142 (the public streaming surface is internal today).
- Suspects to profile, in order: Character/grapheme-based scanning versus byte scanning, per-scalar reader buffering (#135), ARC traffic in tree construction, XPath node-set materialization on every axis step.
Rules
- Optimize only what these numbers indict, one suspect per pass, with the before/after recorded here.
- The corpus generator changes only with a note here, since ratios are only comparable over identical corpora.