Async Ruby VS Concurrent Ruby

Compare Async Ruby vs Concurrent Ruby and see what are their differences.

Async Ruby

An awesome asynchronous event-driven reactor for Ruby. (by socketry)

Concurrent Ruby

Modern concurrency tools including agents, futures, promises, thread pools, supervisors, and more. Inspired by Erlang, Clojure, Scala, Go, Java, JavaScript, and classic concurrency patterns. (by ruby-concurrency)
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Async Ruby Concurrent Ruby
20 13
1,928 5,596
1.2% 0.5%
7.9 8.0
6 days ago 23 days ago
Ruby Ruby
MIT License MIT License
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.

Async Ruby

Posts with mentions or reviews of Async Ruby. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-09-05.
  • EventMachine Performance Spikes
    2 projects | /r/ruby | 5 Sep 2023
    The Async gem is the natural successor, It's actively maintained, and allows you write synchronous code is if it wasn't non-blocking, and most libraries don't need any special support for Async (exceptions are gems with C extensions that do I/O and DB libraries with connection pooling that would otherwise be thread-based).
  • Philosophy of Coroutines
    7 projects | | 1 Sep 2023 uses coroutines and I think in general it’s been a great model with very few downsides in practice.
  • Is ruby really slow?
    2 projects | /r/ruby | 21 Apr 2023
    There's async I/O. Here's a library that leans on Ruby 3's fiber scheduler.
  • Show HN: Goru, an experimental, Go-inspired concurrency library for Ruby
    2 projects | | 3 Apr 2023
    Hey folks, wanted to show this off and get feedback. Still early/experimental but there are quite a few concepts I'm excited about here. This project came about while writing a program in Go and loving its approach to concurrency. Being a long-time Rubyist I immediately started to think about what similar concepts might look like in Ruby.

    I set out with two main design constraints:

    1. Lightweight: I didn't want routines to be backed by fibers or threads. Having been involved some in the async project (, I had some experience using fibers for concurrency but was curious if they could be avoided.

    2. Explicitness: Routine behavior must be written to describe exactly how it is to behave. I always felt like concurrent code was hard to fully understand because of the indirection involved. On the spectrum between tedium and magical I wanted to err more on the side of tedium with Goru.

    Goru routines are just blocks that are called once for every tick of the reactor. It is up to the developer to implement behavior in terms of a state machine, where on each tick the routine takes some action and then updates the state of the routine for the next tick. This fulfills both design constraints:

    1. Because routines are just blocks, they weigh in at about ~345 bytes of memory overhead.

    2. Routine behavior is explicit because it is written as a state machine inside the block.

    Couple more features worth noting:

    * Goru includes channels for buffered reading/writing (similar to channels in Go).

    * Goru ships with primitives for non-blocking IO to easily build things like http servers.

    Curious your thoughts!

  • Twitter (re)Releases Recommendation Algorithm on GitHub
    12 projects | /r/programming | 31 Mar 2023
  • Simple MapReduce that melt my brain (yes, fibers there)
    3 projects | /r/ruby | 16 Mar 2023
    For those who are interested here is the question.
    3 projects | /r/ruby | 16 Mar 2023
  • How does Ruby handle parallel HTTP requests in separate threads?
    3 projects | /r/ruby | 2 Mar 2023
  • Two months into learning Ruby, it is the most beautiful language I ever learned
    5 projects | /r/ruby | 25 Feb 2023
    Welcome! Ruby isn't exactly "dying", but the hype/popularity is definitely fading. This is primarily because Ruby is no longer "new", most of Ruby's popularity came from Rails, and now Rails is no longer the "new hotness". However, Ruby still has lots of awesome features and lots of awesome other libraries and frameworks, such as the new fancy irb gem that uses reline, nokogiri, chunky_png, the async gems, Dragon Ruby, SciRuby, Ronin, and the new Hanami web framework.
  • Efficient IO in Linux with io_uring [pdf]
    5 projects | | 16 Oct 2022

Concurrent Ruby

Posts with mentions or reviews of Concurrent Ruby. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2023-09-11.
  • Exploring concurrent rate limiters, mutexes, semaphores
    2 projects | | 11 Sep 2023
    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!
  • Using Concurrent::Promise while rescuing exceptions in Ruby
    2 projects | | 12 Aug 2022
    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.
  • Ask HN: Any efforts to remove the GIL for Ruby?
    2 projects | | 15 Jun 2022
    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.


  • Ruby 3.1.0 Released
    3 projects | /r/programming | 25 Dec 2021
    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.
  • The right way of parallelizing tasks in a Rails application
    2 projects | /r/rails | 19 Apr 2021
    yes, but `Future` is being deprecated according to the docs. This syntax should possible with Promises (although on my library, it is not working as I expected, I need to look into it hahaha)
  • Best of (Ruby) Gems Series - What's Next? What's Hot?
    19 projects | /r/ruby | 12 Mar 2021
    Concurrent Ruby
  • What is the current state of event driven programming with fibers in ruby?
    10 projects | /r/ruby | 22 Feb 2021 seems to be the current king of concurrency in Ruby. A lot of different concurrency models are implemented so you can pick whichever makes the most sense for you. The downside is that since the library doesn't focus on one model over another, it's probably difficult to learn for beginners.
    10 projects | /r/ruby | 22 Feb 2021
    i think not:

What are some alternatives?

When comparing Async Ruby and Concurrent Ruby you can also consider the following projects:

Celluloid - Actor-based concurrent object framework for Ruby

EventMachine - EventMachine: fast, simple event-processing library for Ruby programs

Polyphony - Fine-grained concurrency for Ruby

Sequel - Sequel: The Database Toolkit for Ruby

render_async - render_async lets you include pages asynchronously with AJAX

net-ssh - Pure Ruby implementation of an SSH (protocol 2) client

ruby-mqtt - Pure Ruby gem that implements the MQTT protocol, a lightweight protocol for publish/subscribe messaging.

ruby-vips - Ruby extension for the libvips image processing library.