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133 lines
4.1 KiB
Markdown
133 lines
4.1 KiB
Markdown
These benchamrks are informal and only intended to give us a general sense of
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the benefit Dart Sass could provide relative to other implementations.
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This was tested against:
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* libsass eee6d59 and sassc 2fcd639 compiled with g++ 4.8.4.
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* Dart Sass dfecdcd on Dart 1.19.1 and Node 4.6.0.
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* Ruby Sass e79f5cf on Ruby 2.2.4p230.
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on Ubuntu x64 with Intel Xeon E5-1650 v3 @ 3.50GHz.
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# Measurements
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I ran five instances of each configuration and recorded the fastest time.
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## Small Plain CSS
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Running on a file containing 4 instances of `.foo {a: b}`:
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* sassc: 0.003s
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* Dart Sass from source: 0.255s
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* Dart Sass from a snapshot: 0.193s
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* Dart Sass on Node.js via dart2js: 0.227s
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* Ruby Sass with a hot cache: 0.130s
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## Large Plain CSS
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Running on a file containing 2^17 instances of `.foo {a: b}`:
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* sassc: 1.972s
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* Dart Sass from source: 2.597s
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* Dart Sass from a snapshot: 2.547s
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* Dart Sass on Node.js via dart2js: 4.971s
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* Ruby Sass with a hot cache: 14.484s
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Based on these numbers, Dart Sass is approximately:
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* 1.3x slower than libsass
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* 2x faster on the Dart VM than on Node
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* 5.7x faster than Ruby Sass
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## Preceding Sparse `@extend`
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Running on a file containing `.x {@extend .y}`, 2^17 instances of `.foo {a: b}`,
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and then `.y {a: b}`:
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* sassc: 2.202s
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* Dart Sass from a snapshot: 2.598s
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* Dart Sass on Node.js via dart2js: 5.309s
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* Ruby Sass with a hot cache: 22.423s
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Based on these numbers, Dart Sass is approximately:
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* 1.2x slower than libsass
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* 2x faster on the Dart VM than on Node
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* 8.6x faster than Ruby Sass
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## Following Sparse `@extend`
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Running on a file containing `.y {a: b}`, 2^17 instances of `.foo {a: b}`,
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and then `.x {@extend .y}`:
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* sassc: 2.207s
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* Dart Sass from a snapshot: 2.569s
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* Dart Sass on Node.js via dart2js: 5.053s
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* Ruby Sass with a hot cache: 22.221s
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Based on these numbers, Dart Sass is approximately:
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* 1.2x slower than libsass
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* 2x faster on the Dart VM than on Node
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* 8.7x faster than Ruby Sass
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## Preceding Dense `@extend`
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Running on a file containing `.bar {@extend .foo}` followed by 2^17 instances of
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`.foo {a: b}`:
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* sassc: 6.703s
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* Dart Sass from a snapshot: 3.922s
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* Dart Sass on Node.js via dart2js: 9.300s
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* Ruby Sass with a hot cache: 40.193s
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Based on these numbers, Dart Sass is approximately:
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* 1.7x faster than libsass
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* 2.4x faster on the Dart VM than on Node
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* 10.3x faster than Ruby Sass
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## Following Dense `@extend`
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Running on a file containing 2^17 instances of `.foo {a: b}` followed by
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`.bar {@extend .foo}`:
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* sassc: 6.636s
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* Dart Sass from a snapshot: 3.644s
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* Dart Sass on Node.js via dart2js: 9.138s
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* Ruby Sass with a hot cache: 39.603s
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Based on these numbers, Dart Sass is approximately:
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* 1.8x faster than libsass
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* 2.5x faster on the Dart VM than on Node
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* 10.9x faster than Ruby Sass
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# Conclusions
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Based on this (admittedly imperfect and non-representative) data, Dart Sass is
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well within the desired performance bounds for large codebases. Because it
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eagerly tracks data for `@extend`s, its worst case is when no `@extend`s are
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present and that tracking proves unnecessary. However, even there it's only 2.2x
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slower than libsass, and well within a reasonable amount of time to process over
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130,000 selectors.
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Because of the novel structuring of `@extend`, we see its relative performance
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increase along with the amount of extension. With only one `@extend` it's almost
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on par with libsass; with hundreds of thousands, it's actually faster.
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It's worth noting that Dart Sass implements `@extend` semantics according to
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[issue 1599][], while other implementations do not. This certainly simplifies
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the implementation and may explain some of the speed gains. However, even if
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other implementations could be faster, it's still the case that Dart Sass is
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*fast enough*.
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It's also interesting to note where Dart Sass falls when run on Node.js. It's
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enough slower than the Dart VM that we probably don't want to position Node.js
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as the primary way of running Sass, but it's still substantially faster than
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Ruby. It probably makes sense to distribute Dart Sass through JS channels as an
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low-overhead introduction, and then make it easy for users to upgrade to the
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Dart version later on for more speed.
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[1599]: https://github.com/sass/sass/issues/1599
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