Files
json/tests/benchmarks/json_view/bench_corpus.cpp
Niels Lohmann 26b7bb2ff4 Compare json_view with yyjson, simdjson, and Boost.JSON
tests/benchmarks/json_view/ holds the comparison with other libraries,
which is not built by CMake or run by CI:

- bench_view.cpp: parse, traverse, select, and dump of twitter,
  citm_catalog, canada, jeopardy, a single tweet, and a JSON-RPC request,
  with json_view, yyjson, simdjson (DOM and On-Demand), Boost.JSON, and
  json::parse; all engines must agree on every document before anything
  is timed, and run interleaved in every round
- bench_corpus.cpp: parse, traverse, and dump of any list of files
- compare.py: builds both against include/ with the libraries of the
  system (or pinned downloads), runs them, and writes the results with
  what is needed to reproduce them (date, commit, CPU, OS, compiler,
  flags, library versions) to results/<date>-<host>.md and .csv; only the
  Python 3 standard library is used
- README.md: how to run it, what is measured, and which features the
  engines have, so the numbers can be read correctly

Boost.JSON is optional (JSON_VIEW_BENCH_BOOST).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-30 15:08:40 +02:00

327 lines
11 KiB
C++

// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++ (supporting code)
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
// Corpus benchmark: the read-only workloads of bench_view.cpp on any list of
// JSON files (for example the benchmark sets of simdjson and yyjson).
//
// ./bench_corpus [--rounds N] file...
//
// For every file, all engines must accept it and agree on a traversal (value
// count, string bytes, sum of numbers) before anything is timed. Workloads:
// parse (build and free a document), traverse (visit every value, convert
// every number), dump (compact), and for json_view also dump with the source
// number text. Results go to bench_corpus.csv.
#include <nlohmann/json_view.hpp>
#if JSON_VIEW_BENCH_BOOST
#include <boost/json.hpp>
#include <boost/json/src.hpp>
#endif
#include <simdjson.h>
#include <yyjson.h>
#include <algorithm>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <functional>
#include <sstream>
#include <string>
#include <vector>
using nlohmann::json;
using nlohmann::json_document;
using nlohmann::json_view;
static volatile double g_sink;
struct stats
{
double num = 0;
std::size_t str = 0, nodes = 0;
};
static void walk(json_view v, stats& st)
{
++st.nodes;
switch (v.type())
{
case json::value_t::object:
for (auto it = v.begin(); it != v.end(); ++it)
{
st.str += it.key().size();
walk(*it, st);
}
break;
case json::value_t::array:
for (const json_view e : v)
{
walk(e, st);
}
break;
case json::value_t::string:
st.str += v.get_string().size();
break;
case json::value_t::number_integer:
st.num += static_cast<double>(v.get<std::int64_t>());
break;
case json::value_t::number_unsigned:
st.num += static_cast<double>(v.get<std::uint64_t>());
break;
case json::value_t::number_float:
st.num += v.get<double>();
break;
default:
break;
}
}
static void walk(yyjson_val* v, stats& st)
{
++st.nodes;
switch (yyjson_get_type(v))
{
case YYJSON_TYPE_OBJ:
{
std::size_t idx, max;
yyjson_val* k, * val;
yyjson_obj_foreach(v, idx, max, k, val)
{
st.str += yyjson_get_len(k);
walk(val, st);
}
break;
}
case YYJSON_TYPE_ARR:
{
std::size_t idx, max;
yyjson_val* val;
yyjson_arr_foreach(v, idx, max, val)
{
walk(val, st);
}
break;
}
case YYJSON_TYPE_STR:
st.str += yyjson_get_len(v);
break;
case YYJSON_TYPE_NUM:
st.num += yyjson_is_sint(v) ? static_cast<double>(yyjson_get_sint(v)) : yyjson_is_uint(v) ? static_cast<double>(yyjson_get_uint(v)) : yyjson_get_real(v);
break;
default:
break;
}
}
static void walk(simdjson::dom::element e, stats& st)
{
++st.nodes;
switch (e.type())
{
case simdjson::dom::element_type::OBJECT:
for (auto f : simdjson::dom::object(e))
{
st.str += f.key.size();
walk(f.value, st);
}
break;
case simdjson::dom::element_type::ARRAY:
for (auto c : simdjson::dom::array(e))
{
walk(c, st);
}
break;
case simdjson::dom::element_type::STRING:
st.str += std::string_view(e).size();
break;
case simdjson::dom::element_type::INT64:
st.num += static_cast<double>(int64_t(e));
break;
case simdjson::dom::element_type::UINT64:
st.num += static_cast<double>(uint64_t(e));
break;
case simdjson::dom::element_type::DOUBLE:
st.num += double(e);
break;
default:
break;
}
}
#if JSON_VIEW_BENCH_BOOST
static void walk(const boost::json::value& v, stats& st)
{
++st.nodes;
switch (v.kind())
{
case boost::json::kind::object:
for (const auto& kv : v.get_object())
{
st.str += kv.key().size();
walk(kv.value(), st);
}
break;
case boost::json::kind::array:
for (const auto& c : v.get_array())
{
walk(c, st);
}
break;
case boost::json::kind::string:
st.str += v.get_string().size();
break;
case boost::json::kind::int64:
st.num += static_cast<double>(v.get_int64());
break;
case boost::json::kind::uint64:
st.num += static_cast<double>(v.get_uint64());
break;
case boost::json::kind::double_:
st.num += v.get_double();
break;
default:
break;
}
}
#endif
static std::string slurp(const std::string& p)
{
std::ifstream f(p, std::ios::binary);
std::stringstream ss;
ss << f.rdbuf();
return ss.str();
}
static bool same(const stats& a, const stats& b)
{
return a.nodes == b.nodes && a.str == b.str && (a.num == b.num || std::fabs(a.num - b.num) <= 1e-9 * std::fabs(a.num));
}
int main(int argc, char** argv)
{
int rounds = 0; // 0: by size
std::vector<std::string> files;
for (int i = 1; i < argc; ++i)
{
if (std::strcmp(argv[i], "--rounds") == 0 && i + 1 < argc)
{
rounds = std::atoi(argv[++i]);
}
else
{
files.push_back(argv[i]);
}
}
std::FILE* csv = std::fopen("bench_corpus.csv", "w");
std::fprintf(csv, "file,bytes,workload,engine,ns\n");
simdjson::dom::parser sj;
for (const auto& path : files)
{
const std::string s = slurp(path);
const std::string name = path.substr(path.rfind('/') + 1);
const simdjson::padded_string ps(s);
// all engines must agree before timing
stats a, b, c, d;
const json_document doc = json_document::parse(s);
walk(doc.root(), a);
yyjson_doc* y = yyjson_read(s.data(), s.size(), 0);
auto sjr = sj.parse(ps);
#if JSON_VIEW_BENCH_BOOST
boost::json::parse_options opt;
opt.numbers = boost::json::number_precision::precise;
boost::json::monotonic_resource mr0;
const boost::json::value bv = boost::json::parse(s, &mr0, opt);
#endif
if (y == nullptr || sjr.error())
{
std::printf("%-34s skipped (an engine rejects it)\n", name.c_str());
yyjson_doc_free(y);
continue;
}
walk(yyjson_doc_get_root(y), b);
walk(sjr.value_unsafe(), c);
#if JSON_VIEW_BENCH_BOOST
walk(bv, d);
#else
d = a;
#endif
yyjson_doc_free(y);
const bool ok = same(a, b) && same(a, c) && same(a, d);
const int r = rounds > 0 ? rounds : static_cast<int>(std::max<std::size_t>(3, std::min<std::size_t>(60, 400000000 / (s.size() + 1))));
struct engine
{
std::string name;
std::function<void()> fn;
};
json_document vd = json_document::parse(s);
yyjson_doc* yd = yyjson_read(s.data(), s.size(), 0);
simdjson::dom::parser sjd;
const simdjson::dom::element se = sjd.parse(ps).value_unsafe();
const std::vector<std::pair<std::string, std::vector<engine>>> workloads =
{
{
"parse", {
{"json_view", [&] { auto x = json_document::parse(s); g_sink = static_cast<double>(x.node_count()); }},
{"yyjson", [&] { yyjson_doc* x = yyjson_read(s.data(), s.size(), 0); g_sink = static_cast<double>(yyjson_doc_get_val_count(x)); yyjson_doc_free(x); }},
{"simdjson DOM", [&] { auto e = sj.parse(ps).value_unsafe(); g_sink = e.is_object(); }},
#if JSON_VIEW_BENCH_BOOST
{"Boost.JSON", [&] { boost::json::monotonic_resource mr; auto v = boost::json::parse(s, &mr); g_sink = v.is_object(); }},
#endif
}
},
{
"traverse", {
{"json_view", [&] { auto x = json_document::parse(s); stats st; walk(x.root(), st); g_sink = st.num; }},
{"yyjson", [&] { yyjson_doc* x = yyjson_read(s.data(), s.size(), 0); stats st; walk(yyjson_doc_get_root(x), st); g_sink = st.num; yyjson_doc_free(x); }},
{"simdjson DOM", [&] { stats st; walk(sj.parse(ps).value_unsafe(), st); g_sink = st.num; }},
#if JSON_VIEW_BENCH_BOOST
{"Boost.JSON", [&] { boost::json::monotonic_resource mr; auto v = boost::json::parse(s, &mr); stats st; walk(v, st); g_sink = st.num; }},
#endif
}
},
{
"dump", {
{"json_view", [&] { std::string o = vd.root().dump(); g_sink = static_cast<double>(o.size()); }},
{"yyjson", [&] { std::size_t n = 0; char* o = yyjson_write(yd, 0, &n); g_sink = static_cast<double>(n); std::free(o); }},
{"simdjson DOM", [&] { std::string o = simdjson::to_string(se); g_sink = static_cast<double>(o.size()); }},
{"json_view (source numbers)", [&] { std::string o = vd.root().dump(-1, ' ', false, json_view::number_format::source); g_sink = static_cast<double>(o.size()); }},
}
},
};
std::printf("%-34s %9zu B%s\n", name.c_str(), s.size(), ok ? "" : " [ENGINES DISAGREE]");
for (const auto& wl : workloads)
{
std::vector<double> best(wl.second.size(), 1e300);
for (int i = 0; i < r; ++i)
{
for (std::size_t k = 0; k < wl.second.size(); ++k)
{
const auto t0 = std::chrono::steady_clock::now();
wl.second[k].fn();
best[k] = std::min(best[k], std::chrono::duration<double, std::nano>(std::chrono::steady_clock::now() - t0).count());
}
}
std::printf(" %-9s", wl.first.c_str());
for (std::size_t k = 0; k < wl.second.size(); ++k)
{
std::printf(" %s %.2f GB/s (%.2fx)", wl.second[k].name.c_str(), static_cast<double>(s.size()) / best[k], best[k] / best[0]);
std::fprintf(csv, "%s,%zu,%s,%s,%.1f\n", name.c_str(), s.size(), wl.first.c_str(), wl.second[k].name.c_str(), best[k]);
}
std::printf("\n");
std::fflush(stdout);
}
yyjson_doc_free(yd);
}
std::fclose(csv);
}