5 ms·

This is a great article and goes to show that statements like "X language is fast" are a little blurry when you put the language in the hands of a skilled devel

This is a great article and goes to show that statements like "X language is fast" are a little blurry when you put the language in the hands of a skilled developer, who can go beyond the standard idioms and surface level understanding of a language to use it like it's another language. At the end of the article, the author wisely chooses to move some objects out of the control of the GC: We are allocating hundreds of thousands Mapping objects, which puts considerable pressure on GC - in reality we don’t really need those objects to be objects... First of all, I changed Mapping from a normal object into a wrapper that points into a gigantic typed array... This suggests to me that we are no longer programming the way one usually does in a dynamically typed, garbage collected language -- and thus it might still be the right decision to move to something like Rust (or Swift or Go) where there is considerably more control over allocation. The author is able to achieve a speed-up of ~4x which is close to the 5.89x achieved by the Rust implementation. There are benefits to having all ones code in the same language; but there are also benefits to switching languages to obtain better ergonomics and safety properties.

vvanders 9y ago
Yeah, this is also where value types are really awesome and you can get the same results from(assuming no strings). Sadly other than C# most of the mainstream GC'd languages don't include them yet as a feature.
- kevingadd 9y ago
  There was even a firm proposal for user-defined value types in JS, but asm.js (and now wasm) took all the air out of the room - though I'm not sure it would have ever gotten implemented in all the browsers anyway, since only perf-sensitive developers care about it. EDIT: I noticed it's actually mentioned in a footnote in the article - the Typed Objects API was really nice, I had a chance to use it for a prototype.
jandem 9y ago
> The author is able to achieve a speed-up of ~4x which is close to the 5.89x achieved by the Rust implementation. This is not a fair comparison because the author made algorithmic improvements that would also improve the wasm version if applied to the Rust code. Source: https://twitter.com/mraleph/status/965616993310265344 https://twitter.com/mraleph/status/965616993310265344
- mraleph 9y ago
  FWIW, quick look at Rust code actually reveals that that implementation is also different algorithmically from what I was optimizing, e.g. it only sorts generatedMappings array. In reality it means that performance of my code should not be that far from what WASM is showing because sorting of originalMappings (which I do eagerly and WASM version does lazily) is one third to one half of the overall runtime. I will try to measure and update the post tomorrow or Wednesday.
- hinkley 9y ago
  If Mark Twain were alive today, the saying would be "Lies, Damned Lies, Statistics, and Benchmarks"
mraleph 9y ago
I should mention in the post that source-map version that relies on WASM actually requires you to manually manage lifetime of SourceMapConsumer object[1], which my change does not actually require because the memory object is encapsulated within SourceMapConsumer itself. I do agree that the way I manage mappings is hardly ergonomic. As mentioned in the post I would prefer to use Typed Objects to access the packed array of mappings, but alas that proposal is stalled. [1] https://github.com/mozilla/source-map#sourcemapconsumerprototypedestroy https://github.com/mozilla/source-map#sourcemapconsumerproto...

vvanders 9y ago

Yeah, this is also where value types are really awesome and you can get the same results from(assuming no strings). Sadly other than C# most of the mainstream GC'd languages don't include them yet as a feature.

kevingadd 9y ago
There was even a firm proposal for user-defined value types in JS, but asm.js (and now wasm) took all the air out of the room - though I'm not sure it would have ever gotten implemented in all the browsers anyway, since only perf-sensitive developers care about it. EDIT: I noticed it's actually mentioned in a footnote in the article - the Typed Objects API was really nice, I had a chance to use it for a prototype.

jandem 9y ago

> The author is able to achieve a speed-up of ~4x which is close to the 5.89x achieved by the Rust implementation. This is not a fair comparison because the author made algorithmic improvements that would also improve the wasm version if applied to the Rust code. Source: https://twitter.com/mraleph/status/965616993310265344 https://twitter.com/mraleph/status/965616993310265344

mraleph 9y ago
FWIW, quick look at Rust code actually reveals that that implementation is also different algorithmically from what I was optimizing, e.g. it only sorts generatedMappings array. In reality it means that performance of my code should not be that far from what WASM is showing because sorting of originalMappings (which I do eagerly and WASM version does lazily) is one third to one half of the overall runtime. I will try to measure and update the post tomorrow or Wednesday.
hinkley 9y ago
If Mark Twain were alive today, the saying would be "Lies, Damned Lies, Statistics, and Benchmarks"

mraleph 9y ago

I should mention in the post that source-map version that relies on WASM actually requires you to manually manage lifetime of SourceMapConsumer object[1], which my change does not actually require because the memory object is encapsulated within SourceMapConsumer itself. I do agree that the way I manage mappings is hardly ergonomic. As mentioned in the post I would prefer to use Typed Objects to access the packed array of mappings, but alas that proposal is stalled. [1] https://github.com/mozilla/source-map#sourcemapconsumerprototypedestroy https://github.com/mozilla/source-map#sourcemapconsumerproto...