json_performance

Performance profiling of JSON libraries

Latest results (November 28, 2023):

Library	Roundtrip Time (s)	Write (MB/s)	Read (MB/s)
Glaze	1.21	988	1016
simdjson (on demand)	N/A	N/A	1134
yyjson	1.45	731	941
daw_json_link	2.73	360	547
RapidJSON	3.50	271	445
json_struct	5.31	167	330
Boost.JSON	5.28	182	276
nlohmann	14.66	83	81

1,000,000 iterations on a single core (MacBook Pro M1) - Compiled with Clang 15

Note: simdjson is great, but can experience major performance losses when the data is not in the expected sequence or any keys are missing (the problem grows as the file size increases, as it must re-iterate through the document). And for large, nested objects, simdjson typically requires significantly more coding from the user.

Note: daw_json_link does not easily support reading with missing keys. So, the code is not tested with this functionality like the rest of the libraries. If missing keys are expected daw_json_link suffers significant performance losses.

Test object (minified for test):

{
   "fixed_object": {
      "int_array": [0, 1, 2, 3, 4, 5, 6],
      "float_array": [0.1, 0.2, 0.3, 0.4, 0.5, 0.6],
      "double_array": [3288398.238, 233e22, 289e-1, 0.928759872, 0.22222848, 0.1, 0.2, 0.3, 0.4]
   },
   "fixed_name_object": {
      "name0": "James",
      "name1": "Abraham",
      "name2": "Susan",
      "name3": "Frank",
      "name4": "Alicia"
   },
   "another_object": {
      "string": "here is some text",
      "another_string": "Hello World",
      "boolean": false,
      "nested_object": {
         "v3s": [[0.12345, 0.23456, 0.001345],
                  [0.3894675, 97.39827, 297.92387],
                  [18.18, 87.289, 2988.298]],
         "id": "298728949872"
      }
   },
   "string_array": ["Cat", "Dog", "Elephant", "Tiger"],
   "string": "Hello world",
   "number": 3.14,
   "boolean": true,
   "another_bool": false
}

ABC Test (Out of Sequence Performance)

In this test the JSON document has keys from "a" to "z", where each key refers to an array of integers from [0, 999]. The document orders the keys from "z" to "a", in reverse order to the expected "a" to "z" layout.

This test demonstrates problems with simdjson and iterative parsers that cannot hash for memory locations. If keys are not in the expected sequence performance seriously suffers, and the problem increases as the size of the document increases.

Hash based solutions avoid this problem and do not suffer performance loss as the JSON document grows in size.

Library	Read (MB/s)
Glaze	640
simdjson (on demand)	110