On Tue, Aug 28, 2012 at 2:47 PM, Shea Levy <[email protected]> wrote:
> Hello,
>
> I would like to write a javascript wrapper around uv_queue_work to deal with
> the case of computationally-expensive functions that shouldn't run in the
> event loop. While obviously this is potentially dangerous, well-written code
> could ensure that the callback called does not touch any state that could
> also potentially be viewed in parallel in the event loop. An example might
> be:
>
> function addInBackground(a,b,cb) {
>   var add;
>   add = function() {
>     return a + b;
>   }
>   uv_queue_work(add,cb);
> }
>
> I know that in my naive guess on how threading could work, this particular
> usage should be safe. My question is: under the hood, is it possible that
> calling the 'add' callback from the work_cb function of uv_queue_work
> manipulates some v8 state in an unsafe way?

Fedor's reply is perhaps a little terse. The answer is "don't do
that", V8 is not thread safe.

You can run JS code in a separate V8 isolate (essentially a separate
VM) but that only works for code that doesn't need to interact with
the outside world.

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