Do await statements unblock synchronously?

Mark S. Miller erights at google.com
Mon Apr 11 20:31:15 UTC 2016


Not necessarily "the next tick", but some future tick. Definitely not in
this tick or the tick in which the promise is resolved. Definitely in its
own tick.

And yes, engines can always do whatever unobservable optimizations they
want.


On Mon, Apr 11, 2016 at 6:00 PM, Jordan Harband <ljharb at gmail.com> wrote:

> As I understand it, `await` always fires in the next tick, if it's
> observable.
>
> The opportunity to optimize that to "same tick" exists if an engine can
> prove it's not observable.
>
> On Mon, Apr 11, 2016 at 9:54 AM, Andrea Giammarchi <
> andrea.giammarchi at gmail.com> wrote:
>
>> > I suppose I'm asking for cases where the await statement's promise is
>> unresolved.
>>
>> isn't that a "forever pending"? then AFAIK it should "forever await" ...
>> right?
>>
>> On Mon, Apr 11, 2016 at 5:50 PM, /#!/JoePea <joe at trusktr.io> wrote:
>>
>>> Is code that follows an await statement supposed to get executed in
>>> the same tick in which the statement's awaited promise is resolved?
>>> F.e.:
>>>
>>> ```js
>>> let resolve = null
>>> const somePromise = new Promise(r => resolve = r)
>>>
>>> ~async function() {
>>>   await somePromise
>>>   doSomething()
>>> }()
>>>
>>> // ... time passes
>>> resolve()
>>> ```
>>>
>>> Should `doSomething()` fire in that same tick as when `resolve()` is
>>> called? I already know that if this is true, there's at least one
>>> exception: `await Promise.resolve()`, in that the await statement must
>>> still defer to a future tick even though the given Promise is already
>>> resolved. I suppose I'm asking for cases where the await statement's
>>> promise is unresolved.
>>>
>>> - Joe
>>> _______________________________________________
>>> es-discuss mailing list
>>> es-discuss at mozilla.org
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>>>
>>
>>
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>
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-- 
    Cheers,
    --MarkM
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