Proposal of Multithread JavaScript

Leo Dutra leodutra.br at gmail.com
Wed Nov 2 14:09:56 UTC 2016


​There's nothing about threading that is not problem with Event loop.
I'd say there's even less problems.

The proposal is a seamless behaviour, equals to what we have now.

Message passing is not a problem of JS developer in the case, but a
V8/WhateverMonkey problem.

Changing a value inside a multithread async MUST behave in the same way of
a change inside a single threaded async. The same way, non-referenced
variables SHALL NOT be scoped in the thread. This is not Java with
volatiles. This is the plain old JS with clojures, openess and loose bare
metal control.

Thread interruption is a bad practice anyway. And we could have a Mutex
class for the specific case or another idea.

Workers are evented and started, not pooled and easy to use.
​


*Leo Dutra, **on **Facebook <http://www.facebook.com/leodutra.br>
**and LinkedIn
<https://www.linkedin.com/in/leobr>*

2016-11-02 11:57 GMT-02:00 Bradley Meck <bradley.meck at gmail.com>:

> We need to be careful about this, I would never condone adding threading
> that could share variables that were not intended to be multi-threaded, as
> such variable access outside of your `parallelize` construct/syntax would
> need to be message passing when talking to something that is not already
> written as a parallel structure. A notable thing here is that Shared Memory
> and Atomics that are in ECMA Stage 2 : https://github.com/tc39/ecma
> script_sharedmem which would probably need to land prior to me condoning
> any shared mutable state.
>
> Historically, all JS implementations are based upon a job queueing system
> described by the Event Loop. This is very different from parallelism which
> could have shared mutable state. All code is guaranteed to have exclusive
> access to variables in scope until it finishes running, and that the
> content of those variables will not change from preemption (there are cases
> where this is not true in the browser with a live DOM). There are
> alternative discussion recently on Workers : https://esdiscuss.org/topic/
> standardize-es-worker . I might look there first.
>
> In particular, I would suggest taking a look at problems of
> synchronization, locking, and preemption breaking existing code a bit
> rather than just stating that green threads are the way to go.
>
> On Wed, Nov 2, 2016 at 8:45 AM, Leo Dutra <leodutra.br at gmail.com> wrote:
>
>> ECMA introduced Promises and async-await in JS. This improves coding in
>> an amazing way, reducing the control developers need to wrap an AJAX call
>> or async I/O.
>>
>> JavaScript used to be script and not a language. Classes, workers, sound
>> control, GL rendering, Node.js modules (with OS conversation), incredible
>> GC strategies and compilation on V8 and Mozilla "monkeys"... the list goes
>> on and on.
>>
>> Almost all the features provided by old mature platforms, like Java, .NET
>> and etc. For browsers, the newest JS features provide consistent tools for
>> productivity and quality code.
>>
>> But there's a huge step to accomplish.
>>
>> ECMA introduced workers. Node.js came up with streams, native process
>> spawn and libuv thread pool. This is a lot, but not enough.
>>
>> All I hear about Node.js is how it is great for quick message I/O and bad
>> for aggregations and impossible for parallel tasking. Again, we have
>> workers and processes, but not green threads.
>>
>> I invite you to take a quick look at Akka and OTP (Erlang). More than it,
>> I will argument: workers and process spawn are the latent desire for
>> parallel and starting one of these are not "cheap" or waiting in a pool.
>>
>> We use streams extensively in Node.js and most frameworks hides it from
>> us. Call it magic, I call it pragmatism.
>>
>> Now, async, await, Promises ("Futures")... we can make it all work in
>> parallel.
>>
>> This would explore more libuv in Node.js and browsers could handle it
>> too, seamlessly.
>>
>> Each function could be run in a green thread, pulled from a browser/libuv
>> pool, allowing Node.js and browsers to process aggregations and heavy
>> rendering without heavy start costs and complicated message control through
>> events.
>>
>> More, I ask why not, and "single thread nature of JS" looks more like a
>> bad legacy from old browsers. We can do it in pieces, like the proposed
>> async-await and, on better days, provide a Parallel API (something like *parallelize(()
>> -> { // parallel stuff here })*).
>>
>> I wanna leave you with the possibilities in mind and bully this single
>> thread dogma.
>>
>> You have been told.
>>
>> *Leo Dutra, **on **Facebook <http://www.facebook.com/leodutra.br> **and LinkedIn
>> <https://www.linkedin.com/in/leobr>*
>>
>> _______________________________________________
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>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
>
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