nio4r VS Concurrent Ruby

One option to solve my problem was to use nio4r's ByteBuffer class, but it felt weird to have to use an I/O gem just for its ByteBuffer class (although I was using the gem already anyway). I mean, it'd probably have worked.

nio4r

After this, I took a look at the semaphore class in the popular library, concurrent-ruby to see how they implement it, and I learnt about something new: condition variables. And Ruby comes with this included!

https://github.com/ruby-concurrency/concurrent-ruby has great docs if someone is looking for alternatives.

I wonder how this would compare to using concurrent-ruby under ruby 2.7, especially in a real-world setting (where the calls are actually to external services that return and buffer data, instead of just sleep). The author says that he's felt that ruby threads "feel easy to mess up," but I've found that concurrent-ruby makes it pretty simple, and performant enough even with the GIL.

As I could not find a clear example about how to rescue exceptions from Concurrent::Promises (part of the Concurrent Ruby gem ) I read through the documentation and here are two examples: one that documents success case and one that shows what is happening when there is an error.

In a sense the GIL (or actually GVL as it's called in current ruby versions) has already been removed for ruby.

It's only the original MRI Ruby that still has it several over Ruby implementations already removed it. e.g. JRuby.

Concurrent-Ruby[1] is probably a good place to start if you want to work with GVL free ruby on JRuby. It's quite well supported and is currently used by Rails.

If you just want async or non-blocking IO I'd take a look at the Async Gem[2]. It looks pretty solid in Ruby > 3.0 and it's been invited by Matz to be part of the stdlib, which I think is a pretty good endorsement.

For MRI itself I don't think it's likely they'll ever remove the GVL. Ractors are probably a better solution for CPU concurrency in the long run, although I think they're pretty experimental currently.

1. https://github.com/ruby-concurrency/concurrent-ruby

I like how the article exposes you to tools to prove/disprove the problem. I would have hoped it introduced to tools like concurrent ruby and the use of atomics like u/Freeky already mentioned though.

Using conccurrent-ruby, how can I execute a set of promises and then get the results?

I’d highly recommend the concurrent-ruby gem that has implementations of various metaphors of concurrency, from async to promises, as well as edge features such as actors.

You may want to consider using something like concurrent-ruby that provides nice abstractions over multithreading.