This is my favorite version of this so far.
this post was submitted on 28 Jan 2024
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I PROMISE the rest will come eventually
that is going to take some RESOLVE
You're just being lazy.
Async are lazy loaded by design in rust, so... Yeah
You must .await before you can have the Result. Then you can use ?
For those who don't get it, it's the "stop doing science" meme.
I'm actually laughing out loud at the amount of whitespace because ~~thread~~ routine is still executing lmao
I honestly don't know, why async got so popular. It seems like the entire reason for doing it was that some blokes were hellbent on using JS on a server and couldn't fathom that a second thread might be a good idea.
If you are waiting for IO, why would you block your current thread and not let it do something else? Async does not only exist in JS.
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After using both extensively I would argue async code is easier to read. It has a lot less nesting. And generally easier to read code is a good thing so I'm all for async.
A huge amount of time in apps is spent waiting for IO, database or web requests to complete.
Async prevents locking a thread during this wait.
If you're handling a large amount of requests in a web server, for example, it allows other requests to progress while waiting for these operations.
Threads are also expensive to start and manage.
Also handling threads manually is a pain in the ass.
Async prevents locking a thread during this wait.
That's a very common misconception. async is just a scheduling tool that runs at the end of event loop (microtask queue). It still runs on the main thread and you can still lock up your UI. You'd need Web Workers for actual multi-threading.
It can lock up a UI doing cpu bound work. Making a web request, no. Preventing the ui thread from waiting on native IO is what async was created for.
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Because the alternative is a series of ridiculously nested call backs that make code hard to read and manage?
I honestly can't fathom how anyone would dislike async programming.
Async is good because threads are expensive, might aswell do something else when you need to wait for something anyways.
But only having async and no other thread when you need some computation is obviously awful.. (or when starting anothe rthread is not easily manageable)
Thats why i like go, you just tell it you want to run something in parallel and he will manage the rest.. computational work, shift current work to new thread.. just waiting for IO, async.
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Ok, I'm a c# developer and I use async await quite extensively. Is it different in JS? Or am I missing something?
Nah, they're very similar, really. You generally kick IO heavy stuff you don't need immediately off to async await.
There are a few more applications of it in C# since you don't have the "single thread" to work with like in JS. And the actual implementation under the hood is different, sure. But conceptually they're similar. Pretty sure JS was heavily influenced by C#'s implementation and syntax.
Async rust with the Tokio Framework is pretty cool. Need none of that JS bloat for async.
Honestly I can't wrap my head how to effectively put computation into a thread, even with Tokio.
All I want is something like rayon where you got a task queue and you just yeet tasks into a free thread, and await when you actually need it
Might be too much JS/TS influence on me, or that I can't find a tutorial that would explain in a way that clicks for me
Tokio specifically says not to use it for CPU intensive tasks and rayon would be better for this: https://tokio.rs/tokio/tutorial
Speeding up CPU-bound computations by running them in parallel on several threads. Tokio is designed for IO-bound applications where each individual task spends most of its time waiting for IO. If the only thing your application does is run computations in parallel, you should be using rayon. That said, it is still possible to "mix & match" if you need to do both. See this blog post for a practical example
Tokio is for concurrency, not parallelism. Use it for IO stuff. They say rayon is good for that, but I haven't used that. If you just want something simple, I'd recommend working with threadpool.
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Imagine a webser or proxy and for every incoming request it creates an new thread 💣
Yes you're right if it's a second or third thread it is/may be fine. But if you're i/o bound and your application has to manage quite a lot of that stuff in parallel, there is no way around delegating that workload to the kernel's event loop. Async/Await is just a very convenient abstraction of that Ressource.
async/await is just callback() and queueMicrotask wrapped up into a neat package. It's not supposed to replace multi-threading and confusing it for such is dangerous since you can still stall your main/UI thread with Promises (which async also wraps).
(async and await are also technically different things, but for the sake of simplicity here, consider them a pair.)
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async/await could be useful if one creates an entire program designed on and for it, but it stops being acceptable as soon as I need two .thens inside of each other because I tried to use fetch in a non-async app without race conditions
Observables are your friends
Honestly, I don't get it.
Is it about the syntax sugar? Would you like to use callbacks instead?
Async programming is when you achive concurrency even with one thread. It's needed. There's no alternative to this.
We're here asyncronously waiting for the rest of the meme.
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