Commit Graph
2 Commits
Author SHA1 Message Date
Niels Lohmann b38c056204 json_view benchmarks: compare fairly and state what each row means
- bench_view: add "(editable)" rows for json_editable_document and a
  parse+dump workload, so the cost of lazy float conversion shows next to the
  parse row (the traverse workload already includes the parse). Check that
  all engines' dumps agree where outputs are comparable.
- compare.py: add --aligned, which also builds and runs with aligned code and
  reports both tables, so code-layout artifacts become visible. Off by
  default; the default output is unchanged. Not run end to end yet.
- README: say which engines are like-for-like peers (yyjson, simdjson DOM) and
  which are mutable reference points (Boost.JSON, json::parse, the editable
  json_view); explain the lazy float conversion and the eager prototype that
  was measured and dropped.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 10:54:04 +01:00
Niels Lohmann 2dc1e54856 Compare json_view with yyjson, simdjson, and Boost.JSON (#5627)
* Compare json_view with yyjson, simdjson, and Boost.JSON

tests/benchmarks/json_view/ holds a comparison with other
libraries, answering the question users ask when they pick one.
It is not built by CMake and not run by CI.

- bench_view.cpp: parse, traverse, select and dump of twitter,
  citm_catalog, canada, jeopardy, a tweet and an RPC request,
  against json_view, yyjson, simdjson, Boost.JSON and json::parse,
  all agreeing and run interleaved.
- bench_corpus.cpp: parse, traverse and dump of any file list.
- bench_edit.cpp: parses, edits through each library's own API,
  and serializes; all outputs must describe the same value.
- compare.py: builds both programs with system or pinned,
  SHA-256-checked downloads, and writes results with the commit,
  CPU, OS, compiler and library versions.
- README.md and a workflow that runs on demand or via a PR label.

Fairness fixes folded in: each engine runs once untimed before
each timed round, so the next one no longer pays for the
previous one's cleanup; dump is also compared with source numbers
against yyjson's raw-number mode; a "simdjson DOM (fresh)" column
and a reused-document column for json_view were added;
compare.py's paths are absolute; downloads use a .part file and a
failed checksum removes the archive.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Make the downloads of json_view's compare.py robust

Hash the archives in chunks instead of reading them into memory, download
with a timeout, extract into a temporary directory that is renamed into
place only after success (a half-extracted directory was trusted forever),
and split CXX and CC into arguments so that values like 'ccache g++' work.
Note at the pins that a SHA-256 mismatch of a GitHub tag archive means
that GitHub regenerated it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Add a timeout and a concurrency group to the json_view benchmarks

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Check the CSV file and the round count in the json_view benchmarks

fopen() of the CSV output was not checked, so an unwritable directory made
fprintf() write to a null FILE*; the round count is parsed with strtol and
clamped instead of atoi.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-22 08:40:33 +02:00