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0 pointsOsiris10y ago0 comments

Some Promise library add support for things like `.timeout` so you can force a promise to reject if the promise takes too long to resolve.

In cases like a node.js server, Promises allow a single node instance to handle thousands of concurrent requests because the event loop isn't blocking waiting for a single IO request to complete, the process can happily do lots of other things while Promises are pending.

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2 comments · 1 top-level

anonymoushn10y ago· 1 in thread

Yes, I expect Promise libraries to support timeouts.

So it's right that promises allow me to do the same thing I would do with sequential code in other languages? If I had the option of using coroutines when would I choose to use promises?

Edit: I'm asking because the context of this thread is that one person said that sequential APIs for asynchronous operations, such as open(2), are pretty nice, and someone else said no they're not pretty nice and we should explicitly deal with the asynchronous nature of operations like open(2) by NOT writing sequential code there.

Shog910y ago

If you have promises OR you have coroutines, your life is good. Either way, you don't have to choose between writing fragile sequential code and writing error-prone synchronization logic.

If you don't have either, then you'll probably end up re-implementing one or the other eventually anyway.

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