json Comparison to Glaze

We need to evaluate the performance of Boost.JSON against Glaze. Pure DOM (json::value) and to/from struct (apples to apples).

Aug 28 '25 02:08 vinniefalco

I actually experimented with it, but then dropped it for some reason I already forgot.

Aug 29 '25 06:08 grisumbras

Local results

Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (direct),363
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),369
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,1381

Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (direct),496
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),353
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,825

Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (direct),640
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),788
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,1880

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (direct),1567
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),307
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,4908

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (direct),491
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),209
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,610

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (direct),2275
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),539
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,8275

Note that I haven't checked that Glaze produces correct outputs yet.

Aug 29 '25 16:08 grisumbras

does glaze have a DOM?

Aug 29 '25 19:08 vinniefalco

Kinda. Their value type is a wrapper over std::variant of std::nullpr_t, bool, double, std::vector, and std::map. I'm adding it to the benchmark too.

Sep 01 '25 11:09 grisumbras

Local results

Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (direct),363
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),369
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,1381

Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (direct),496
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),353
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,825

Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (direct),640
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),788
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,1880

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (direct),1567
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),307
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,4908

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (direct),491
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),209
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,610

Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (direct),2275
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),539
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,8275

Note that I haven't checked that Glaze produces correct outputs yet.

@grisumbras what the numbers mean?

I recently saw a mention of the Glaze library, looked at their benchmark and to be honest its worst benchmark i've seen in a while.

Their benchmark looks so fake that I'm curious about the real numbers.

On the other hand, I know an implementation on top of the Boost Json that does direct stream parsing into values and beats the native Boost Json implementation, maybe later I'll give you the code to add to the benchmark

Sep 12 '25 04:09 kelbon

@grisumbras what the numbers mean?

Megabytes per second. boost (direct) is using Boost.JSON with direct operations. boost (pool) is using Boost.JSON with DOM, monotonic_resource, and value_to/from.

Glaze is indeed very fast when you use it with direct operations (how it was intended to be used).

On the other hand, I know an implementation on top of the Boost Json that does direct stream parsing into values and beats the native Boost Json implementation, maybe later I'll give you the code to add to the benchmark

Can you give a link? If it doesn't break parse_into API, I may integrate it into the library myself.

Now, these are the benchmarks for JSON DOM and Glaze "DOM" (glz::json_t).


Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost,425
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),596
Parse /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,275
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost,356
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),547
Parse /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,229
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost,543
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),1177
Parse /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,328
Parse /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,boost,375
Parse /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,boost (pool),825
Parse /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,glaze,254
Parse /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,boost,831
Parse /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,boost (pool),1814
Parse /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,glaze,591
Parse /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,boost,308
Parse /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,boost (pool),654
Parse /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,glaze,215
Parse /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,boost,289
Parse /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,boost (pool),534
Parse /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,glaze,120
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,boost,459
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,boost (pool),580
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,glaze,214
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,boost,911
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,boost (pool),1106
Parse /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,glaze,425
Parse /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,boost,791
Parse /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,boost (pool),877
Parse /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,glaze,446
Parse /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,boost,223
Parse /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,boost (pool),347
Parse /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,glaze,134
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,boost,317
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,boost (pool),526
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,glaze,212
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,boost,278
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,boost (pool),461
Parse /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,glaze,186
Parse /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,boost,322
Parse /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,boost (pool),555
Parse /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,glaze,167
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost,1635
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,boost (pool),1667
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/apache_builds.json,gcc x64/sse2,glaze,1524
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost,548
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,boost (pool),550
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/canada.json,gcc x64/sse2,glaze,510
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost,1990
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,boost (pool),2093
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/citm_catalog.json,gcc x64/sse2,glaze,1432
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,boost,1697
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,boost (pool),1705
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/github_events.json,gcc x64/sse2,glaze,1893
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,boost,1503
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,boost (pool),1547
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/gsoc-2018.json,gcc x64/sse2,glaze,1886
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,boost,1391
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,boost (pool),1411
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/instruments.json,gcc x64/sse2,glaze,1263
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,boost,461
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,boost (pool),481
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/marine_ik.json,gcc x64/sse2,glaze,305
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,boost,413
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,boost (pool),413
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.json,gcc x64/sse2,glaze,371
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,boost,880
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,boost (pool),887
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/mesh.pretty.json,gcc x64/sse2,glaze,807
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,boost,427
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,boost (pool),426
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/numbers.json,gcc x64/sse2,glaze,514
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,boost,880
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,boost (pool),938
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/random.json,gcc x64/sse2,glaze,516
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,boost,1598
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,boost (pool),1619
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitter.json,gcc x64/sse2,glaze,1369
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,boost,1423
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,boost (pool),1450
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/twitterescaped.json,gcc x64/sse2,glaze,1204
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,boost,1040
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,boost (pool),1086
Serialize /home/grisumbras/dev/boost/libs/json/bench/data/update-center.json,gcc x64/sse2,glaze,727

In this case Glaze parses much slower than Boost.JSON using the default memory resource (which is in turn much slower than when monotonic_reqource is used). Difference in serialization speed is less pronounced. Glaze even outperforms Boost.JSON on numbers.json (that file is a giant array of numbers). This is due to it directly using Dragnobox. I'm considering doing the same for Boost.JSON.

The most obvious conclusion is that Boost.JSON is absolutely superior if you need a DOM. If you can avoid a DOM, Glaze will probably always be faster. There are still other benefits Boost.JSON has, like actual documentation and streaming I/O support.

Sep 12 '25 10:09 grisumbras

Can you give a link? If it doesn't break parse_into API, I may integrate it into the library myself.

First of all, i see you use only gcc in your benchmark, it may be useful to add clang into comparison. On my benchmark, there are cases when gcc 5 times worse than clang

About different solution for direct parsing - it uses parse api from Boost Json, key idea to use recusrive generator coroutine for implementing parsing for all types

So, there are stream_parser:

struct stream_parser {
  boost::json::basic_parser<boostjson_sax_producer> p;

  template <typename T>
  explicit stream_parser(T& t, std::span<byte_t> buf = {});
  void feed(std::string_view data, bool end, io_error_code& ec) {
    p.write_some(!end, data.data(), data.size(), ec);
    ...
  }
};

and boostjson_sax_producer here implemented on top of recursive generator

Then, parsing for concrete type implemented as coroutine, e.g. for vector of T:

  generator_type parse(std::vector<T>& v, sax_token& tok, dd::with_stack_resource r) {
    tok.expect(sax_token::array_begin);
    for (;;) {
      co_yield {};
      if (tok.got == sax_token::array_end)
        break;
      co_yield dd::elements_of(parser_for<T>(v.emplace_back(), tok, r));
    }
  }

Sep 12 '25 13:09 kelbon

I did run benchmarks with Clang too. The results are in the same ballpark. Interestingly, Clang is consistently slower for most benchmarks for me (but not by much).

About different solution for direct parsing - it uses parse api from Boost Json, key idea to use recusrive generator coroutine for implementing parsing for all types

This is very interesting. I obviosuly cannot make it the default implementation in a C++11 library, but this can be a great example in the docs or even an alternative implementation.

Sep 15 '25 09:09 grisumbras