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Re: Sync API for workers

From: Brendan Eich <brendan@mozilla.org>
Date: Tue, 04 Sep 2012 13:59:59 -0700
Message-ID: <50466BCF.5020602@mozilla.org>
To: David Bruant <bruant.d@gmail.com>
CC: Jonas Sicking <jonas@sicking.cc>, "public-webapps@w3.org" <public-webapps@w3.org>, Alon Zakai <azakai@mozilla.com>
David Bruant wrote:
> I can imagine, it sounds hard indeed. Do you have numbers on how it
> affects performance? Or an intuition on these numbers? I don't need to
> be convinced that it affects performance significantly, but just to get
> an idea.

This is not going to be easy to estimate, but you might benchmark 
generator vs. non-generator code in the latest SpiderMonkey.

I don't think we need quantification, though. Alon's right, the 
optimizing VMs are not focused on uncommon code other than what's in the 
dopey industry-standard benchmarks.

> I remember that at some point (your JSConf.eu talk last October), in
> order to be able to compile through Emscripten, the source codebase (in
> C/C++) had to be manually tweaked sometimes. Is it still the case? If
> it's an acceptable thing to ask to authors, then would there be easy
> ways for authors to make their IO blocking code more easily translated
> to async JS code? I'm pessimistic, but it seems like an interesting
> question to explore.

BananaBread required zero Cube 2 changes, IIRC. Other Emscripten 
examples are also pure compilation.

Forget it. Inversion of control flow is hard enough and error prone that 
developers won't do it. It's the #1 reason Mozilla's Electrolysis 
project is paused indefinitely. The SuperSnappy work (threads, not 
processes) preserves most execution model compatibility, and avoids 
requiring programmers writing Firefox XUL front-end and add-on code from 
having to manually callback-CPS their code (on every DOM access!).

/be
Received on Tuesday, 4 September 2012 21:00:26 GMT

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