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Async Everything is a bad language. Async/await was a terrible idea for fixing JavaScript's lack of proper blocked threading that is currently being bolted ont

Async Everything is a bad language. Async/await was a terrible idea for fixing JavaScript's lack of proper blocked threading that is currently being bolted onto every language. It splits every language and every library-ecosystem in half and will cause pains for many years to come. Everyone who worked with multi-threading outside of JavaScript knows that using actors/communicating sequential processes is the best way to do multi-threading. I recently found an explanation for that in Joe Armstrong's thesis. He argues that the only way to understand multi-threaded programs is writing strictly sequential code for every thread and not muddling all the code for all the threads in one place: "The structure of the program should exactly follow the structure of the problem. Each real world concurrent activity should be mapped onto exactly one concurrent process in our programming language. If there is a 1:1 mapping of the problem onto the program we say that the program is isomorphic to the problem. It is extremely important that the mapping is exactly 1:1. The reason for this is that it minimizes the conceptual gap between the problem and the solution. If this mapping is not 1:1 the program will quickly degenerate, and become difficult to understand. This degeneration is often observed when non-CO languages ["non concurrency-oriented", looking at you JavaScript!] are used to solve concurrent problems. Often the only way to get the program to work is to force several independent activities to be controlled by the same language thread or process. This leads to a inevitable loss of clarity, and makes the programs subject to complex and irreproducible interference errors." [0] [0] https://erlang.org/download/armstrong_thesis_2003.pdf https://erlang.org/download/armstrong_thesis_2003.pdf There is also a good rant against async/await by Ron Pressler who implemented project loom in java: https://www.youtube.com/watch?v=oNnITaBseYQ https://www.youtube.com/watch?v=oNnITaBseYQ

mrkline 3y ago
> Async/await was a terrible idea for fixing JavaScript's lack of proper blocked threading that is currently being bolted onto every language. As fun as it is to hate on JavaScript, it's really interesting to go back and watch Ryan Dahl's talk introducing Node.js to the world (https://www.youtube.com/watch?v=EeYvFl7li9E https://www.youtube.com/watch?v=EeYvFl7li9E). He's pretty ambivalent about it being JavaScript. His main goal was to find an abstraction around the epoll() I/O event loop that didn't make him want to tear his eyes out, and he tried a bunch of other stuff first.
- yankput 3y ago
  It’s so interesting that the async/await stuff basically makes his presentation points meaningless? if you’re just using the async/await why use the callback style in the first place… but I get it, you can always go back to the promises and callbacks if you want.
- chubot 3y ago
  He was strongly advocating callbacks with node.js, which is understandable given the time. But a few years later when he wrote some Go code, he said that's a better model for networked servers (sorry no reference right now, it was in a video I watched, not sure which one) JS callbacks are indeed better than C callbacks because you can hold onto some state. Although I guess the capture is implicit rather than explicit, so some people might say it's more confusing. I'm pretty sure Joyent adopted and funded node.js because they were doing lots of async code in C, and they liked the callback style in JavaScript better. It does match the kind of problems that Go is now being used for, and this was pre-Go. But anyway it is interesting how nobody really talks about callbacks anymore. Seems like async/await has taken over in most languages, although I sorta agree with the parent that it could have been better if designed from scratch.
- fzeindl 3y ago
  > As fun as it is to hate on JavaScript, it's really interesting to go back and watch Ryan Dahl's talk introducing Node.js to the world Agreed. JavaScript was actually my first language after TurboPascal in 1996. I was also there listening to the first podcasts when node came out. JavaScript is a very interesting language, especially with it's prototype memory model. And the eventloop apart from the language is interesting as well. And it's no coincidence Apple went as far as baking optimizations for JavaScript primitive operations into the M1 microcode. But I still think multithreading is best done by using blocking operations. NIO can be implemented on top of blocking IO as far as I know but not the other way round. Also, sidenote, I think JavaScript's only real failure is the lack of a canonical module/import system. That error lead to countless re-implementations of buildsystems and tens of thousands of hours wasted debugging.
  - 3y ago
seabrookmx 3y ago
async/await actually originated in C#, not Javascript. C#'s author, Anders Hejlsberg also authored Typescript. Typescript's additional features like classes, arrow functions and async/await eventually crept into ES6+. I actually think it was a great solution in JS/TS given it's a single threaded event loop. The lower level the language the worse of an abstraction it is though. So I think most of the complaints here about async Rust are valid.

mrkline 3y ago

> Async/await was a terrible idea for fixing JavaScript's lack of proper blocked threading that is currently being bolted onto every language. As fun as it is to hate on JavaScript, it's really interesting to go back and watch Ryan Dahl's talk introducing Node.js to the world (https://www.youtube.com/watch?v=EeYvFl7li9E https://www.youtube.com/watch?v=EeYvFl7li9E). He's pretty ambivalent about it being JavaScript. His main goal was to find an abstraction around the epoll() I/O event loop that didn't make him want to tear his eyes out, and he tried a bunch of other stuff first.

yankput 3y ago
It’s so interesting that the async/await stuff basically makes his presentation points meaningless? if you’re just using the async/await why use the callback style in the first place… but I get it, you can always go back to the promises and callbacks if you want.
chubot 3y ago
He was strongly advocating callbacks with node.js, which is understandable given the time. But a few years later when he wrote some Go code, he said that's a better model for networked servers (sorry no reference right now, it was in a video I watched, not sure which one) JS callbacks are indeed better than C callbacks because you can hold onto some state. Although I guess the capture is implicit rather than explicit, so some people might say it's more confusing. I'm pretty sure Joyent adopted and funded node.js because they were doing lots of async code in C, and they liked the callback style in JavaScript better. It does match the kind of problems that Go is now being used for, and this was pre-Go. But anyway it is interesting how nobody really talks about callbacks anymore. Seems like async/await has taken over in most languages, although I sorta agree with the parent that it could have been better if designed from scratch.
fzeindl 3y ago
> As fun as it is to hate on JavaScript, it's really interesting to go back and watch Ryan Dahl's talk introducing Node.js to the world Agreed. JavaScript was actually my first language after TurboPascal in 1996. I was also there listening to the first podcasts when node came out. JavaScript is a very interesting language, especially with it's prototype memory model. And the eventloop apart from the language is interesting as well. And it's no coincidence Apple went as far as baking optimizations for JavaScript primitive operations into the M1 microcode. But I still think multithreading is best done by using blocking operations. NIO can be implemented on top of blocking IO as far as I know but not the other way round. Also, sidenote, I think JavaScript's only real failure is the lack of a canonical module/import system. That error lead to countless re-implementations of buildsystems and tens of thousands of hours wasted debugging.
- 3y ago

seabrookmx 3y ago

async/await actually originated in C#, not Javascript. C#'s author, Anders Hejlsberg also authored Typescript. Typescript's additional features like classes, arrow functions and async/await eventually crept into ES6+. I actually think it was a great solution in JS/TS given it's a single threaded event loop. The lower level the language the worse of an abstraction it is though. So I think most of the complaints here about async Rust are valid.