[eyelidlessness]

async (the keyword) is doing fantastic because it’s better than all of the available alternatives. Those alternatives:

- ad hoc callbacks, which had a great Result-ish type signature but really do warrant the “hell” in “callback hell”

- Promise APIs, which are semantically equivalent to async the keyword, unless you care about call stacks, and have a lot of the same hellish problems as the ad hoc callbacks they were meant to address (less nesting! same everything else!)

- Um fibers? Good luck making sense out of whatever that’s doing. It’s a good idea, but it’s also all opaque magic when you try using it.

- Actual threads and child processes… there are valid use cases, and they’re worth pursuing if you have a valid use case, but the facilities for development with them are basically “here’s a bunch of low level concepts that closely mirror their system level counterparts, hope you know/figure out what you’re doing!”

[ithrow]

By async I was referring to node's asynchronous event-driven runtime abstraction which the GP refers to as an ugly hack. I'm not sure if this abstraction is better than all of the available alternatives if you compare it to high-level features multi-threaded runtimes offer like thread-safe collections, atomic updates, concurrent hash maps, immutability, structured concurrency, etc... as in Java/Clojure. Most Java programmers don't work with the low-level thread primitives.

The author of esbuild gave up trying to code esbuild with nodejs/worker threads and switched to Go for a less limited/restricted concurrency environment.

[eyelidlessness]

> By async I was referring to node's asynchronous event-driven runtime abstraction which the GP refers to as an ugly hack.

Okay with that clarification I can agree it’s a good model, given its constraints. The event loop with async IO in the abstract is a good way to model a single process/thread workload for many use cases that fit it.

> I'm not sure if this abstraction is better than all of the available alternatives if you compare it to high-level features multi-threaded runtimes offer like thread-safe collections, atomic updates, concurrent hash maps, immutability, structured concurrency, etc... as in Java/Clojure.

Clojure’s solution to concurrency is a breath of fresh air, regardless of your execution environment, because its state transactional semantics are great whether your concurrency is in one process/thread or spread across many. I can’t speak to typical Java solutions, but my general sense is they’re higher level and more powerful than Node’s for actually crossing process/thread boundaries, but subject to most of the shared state problems Java has even in a single process/thread.

> The author of esbuild gave up trying to code esbuild with nodejs/worker threads and switched to Go for a less limited/restricted concurrency environment.

After a lot of exploration of Node worker threads, I’d probably similarly look elsewhere if I had a workload suited to it. You can do a lot with Node worker threads with a lot of special tuning for a use case, and I even have some proof of concept code demonstrating that it can be much better than common usage. But I put it on hold because the complexity of making it perform well is very high compared to optimizing the single thread default.