Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Use rb_str_buf_new() to improve JSON.parse() performance with short string #452

Closed
wants to merge 1 commit into from
Closed

Use rb_str_buf_new() to improve JSON.parse() performance with short string #452

wants to merge 1 commit into from

Commits on Nov 29, 2020

  1. Use rb_str_buf_new() to improve JSON.parse() performance with short s… 

    …tring

`rb_str_buf_new` always performs allocation twice (at `str_alloc` and `ALLOC_N`).
And the method does not allow embeded string even if the string is short enough.

```
VALUE
rb_str_buf_new(long capa)
{
    VALUE str = str_alloc(rb_cString);

    if (capa < STR_BUF_MIN_SIZE) {
        capa = STR_BUF_MIN_SIZE;
    }
    FL_SET(str, STR_NOEMBED);
    RSTRING(str)->as.heap.aux.capa = capa;
    RSTRING(str)->as.heap.ptr = ALLOC_N(char, (size_t)capa + 1);
    RSTRING(str)->as.heap.ptr[0] = '\0';

    return str;
}
```

Therefore, this PR uses `rb_str_new` instead to reduce the allocation with a short string.
This PR will improve the performance about 16%.

### Before
```
Warming up --------------------------------------
   short_string_json    10.660k i/100ms
    long_string_json    10.058k i/100ms
Calculating -------------------------------------
   short_string_json    106.992k (± 1.4%) i/s -    543.660k in   5.082355s
    long_string_json    102.273k (± 1.0%) i/s -    512.958k in   5.016081s
```

### After
```
Warming up --------------------------------------
   short_string_json    12.413k i/100ms
    long_string_json    10.457k i/100ms
Calculating -------------------------------------
   short_string_json    124.316k (± 0.8%) i/s -    633.063k in   5.092705s
    long_string_json    105.665k (± 0.9%) i/s -    533.307k in   5.047540s
```

### Test code
```ruby
require 'benchmark/ips'
require 'json'

short_string_json = {
  "a" => "b" * 23,
  "a" * 23 => "b"
}.to_json.freeze

long_string_json = {
  "a" => "b" * 50,
  "a" * 50 => "b"
}.to_json.freeze

Benchmark.ips do |x|
  x.report("short_string_json") { JSON.parse(short_string_json) }
  x.report("long_string_json") { JSON.parse(long_string_json) }
end
```
    @Watson1978
    Watson1978 committed Nov 29, 2020
    Configuration menu
    Copy the full SHA
    4c4e32e View commit details
    Browse the repository at this point in the history