[SomeCallMeTim]

Rust does sound interesting, but it doesn't seem to be focused on the areas that I need right now.

Go has GoRoutines, which are light threads; they can be executed on multiple CPU threads, but by default Go only allocates one CPU thread per physical CPU, even if you allocate tens of thousands of GoRoutines.

For the kind of networking server code I'm writing, light threading is far more efficient than using an OS thread per connection. 25-50x faster at higher server loads.

That's why I've ignored Rust to date; if Rust has light threading built in, but no one is talking about it (haven't found anything but real threads in my quick Google searches), then I'll take a look. Otherwise it will need to wait for me to have a task that Rust would be good for, and I'll stick with Go and TypeScript for the problems I'm solving right now.

[vvanders]

Ah, sounds like Erlang/Elixir would be a better fit since the BEAM is the king of lightweight threads/processes.

You said C++ so that's why I suggested Rust, generally a GC tends to preclude spaces where C++ excels which is why I would think you'd want to try something other than Go.

On the Rust side there's things like mio for fast io but coroutine/light threads aren't really a focus afaik. I would still think you could get solid performance (and much better memory use, see Dropbox's replacement of Go) with an event based Rust system although that's not really my area of expertise :).

[15155]

I am sure that a Rust team member will be here soon to set the record straight, however, my take:

> Rust side there's things like mio for fast io but coroutine/light threads aren't really a focus afaik

IO and concurrency/parallelism models are a very difficult topic to really discuss and quantify performance around.

The highest-known-performance network server architecture revolves around edge-triggered epoll/kqueue (evented, async IO) and state machines (eschewing the stack entirely.)

pthreads (speaking exclusively about POSIX here - Windows threads are far heavier-weight than pthreads) suffer the cost of context switching due to large (by default - this can be configured) stack sizes.

This is one reason why languages like Go and Erlang have their own stack and lightweight process (greenthread) implementations.

For the record: Rust had green threading, and I believe it was removed due to the overhead relating to supporting it. The simple fact that you really cannot control or know when FFI calls will block (libc included) or not makes greenthreading tricky.

The trickier thing, IMO, relating to async IO is just the compatibility aspect:

- Golang/Erlang control compatibility by offering entire ecosystems built around their greenthread models.

  - Golang even goes as far as replacing the vast majority of libc and much of what you would want to call out to C for.

- Rust, being a systems language, cannot dictate "all code must use async IO and this specific reactor/event loop implementation," the stdlib is too small (by design), calls to libc are too pervasive.

With all of that being said:

- I personally believe Rust core should adopt a blessed async IO system (event loop, OS-level abstraction layers, basically mio) that all code could opt into using. - Additionally, it would be lovely if, on top of said system, compiler support for stackless coroutines (a la async/await) and a multithreaded reactor were implemented.

I love Rust, but I can't use it for network server related tasks until this part of the ecosystem is more developed and made more consistent.

mio is the de facto stdlib AIO implementation, but there's still a lot of fragmentation, and many libs still use the blocking networking builtins, rendering them incompatible.

[SomeCallMeTim]

I've been reading about Elixir recently, yes. Thanks for mentioning it, though. I'll have to look at it at some point, but since my code is primarily run-in-a-browser, I'm currently stuck with compile-to-JavaScript languages. I'm concerned that Elixir is too functional for my tastes (I find Haskell to be too pure (and slow) to be really usable for most tasks I work on, for instance), but I will give it a look at some point.

The entire point of writing in Go or Elixir would be to avoid needing to write an event based system in Rust (or C). Writing code as if it's imperative but getting the speed of an event-based system is what I'm looking for. Event-based systems are notoriously hard to reason about and debug.

[krakensden]

You just can't be happy if someone else is using Go, can you.

[vvanders]

The parent is already experienced in Go and expressed interests in other languages, excuse me for indulging them :).