Commit Graph
6 Commits
Author SHA1 Message Date
Niels Lohmann 540eb7c5f2 Compare JSON libraries by use case in the json_view harness
bench_all and bench_rs now time use cases (validate, sum, select, edit,
minify, write) instead of library functions. Every library may solve a
use case in every way it offers; each variant's result is checked, and
three malformed inputs give its validation level (full, no UTF-8,
partial). summarize.py reports each library's fastest fully validating
variant and a faster one at a lower level, as text and as JSON.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:29:49 +01:00
Niels Lohmann c24c177583 docs: dump comparison and split acknowledgments in the 3.13.0 post
- a dump workload in bench_all and bench_rs: each engine writes a
  document parsed beforehand, and every output must read back with
  bit-identical numbers; an optional argument selects one workload
- the post's comparison gains a write table, a throughput chart, a dump
  row for all three configurations, and the x86-64 cases it loses
- the thanks section is split into adapted code and borrowed ideas

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:29:48 +01:00
Niels Lohmann 7341f127d3 docs: compare json_document with Glaze, sonic, RapidJSON and Rust parsers
Extends the comparison in "How 3.13.0 got faster" from yyjson, simdjson and
Boost.JSON to eleven engines: sonic-cpp, RapidJSON and Glaze (generic DOM,
lazy_json, reading into structs) in C++, sonic-rs, simd-json and serde_json in
Rust. Measured on an Apple M1 Max (Apple clang 21, Rust 1.99) and an x86-64
Haswell server (GCC 13, Clang 18). Every engine must return the same values,
string bytes and bit-identical number sums before it is timed.

The post now answers whether json_document is the fastest parser: it is the
fastest document parser at parse+dump everywhere and at parsing on Apple
silicon, ties with simdjson's DOM on x86-64, and loses to simdjson On-Demand
and Glaze structs when only a few fields are read.

tests/benchmarks/json_view/others holds the programs (bench_all.cpp, the Rust
crate with its Cargo.lock), summarize.py and the pinned versions and checksums.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:29:46 +01:00
Niels Lohmann d20c4dcd89 json_view benchmarks: compare fairly and state what each row means (#5914)
- 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>
2026-10-30 15:20:12 +01:00
Niels Lohmann e5fe4ebdd2 json_view: from_json() of the macros reads views directly (#5922)
get<T>() and get_to() of a view call T's from_json() with the view itself
when that from_json() accepts views but not an unrelated probe type, and
fall back to materialize() otherwise. The from_json() functions of the
NLOHMANN_DEFINE_TYPE_*, NLOHMANN_DEFINE_DERIVED_TYPE_* and
NLOHMANN_JSON_SERIALIZE_ENUM(_STRICT) macros accept basic_json values and
views; a derived type whose base reads only json reads the base part
through materialize(). The library's own from_json() overloads are not
called with views: from_json() of a view (and of the probe) only looks up
functions by ADL.

New public trait nlohmann::is_json_view<T>, and the member type
basic_json_type of basic_json_view. With duplicate keys, the members of
such a T are those the view's lookups find (the first ones).

bench_decode.cpp measures decoding into structs (4-6x faster than
materialize().get<T>() on twitter, citm_catalog, and synthetic records).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:31 +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