Concurrent Ruby VS Async Ruby

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

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)

Async Ruby

An awesome asynchronous event-driven reactor for Ruby. (by socketry)
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Concurrent Ruby Async Ruby
17 23
5,731 2,249
0.1% 0.7%
7.0 8.8
about 2 months ago 12 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.

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 2025-02-11.
  • Ruby, Rails, Multi-threading e Puma: Como tudo isso se conecta?
    2 projects | dev.to | 11 Feb 2025
  • Concurrent-ruby (async) S3 files download
    1 project | dev.to | 17 May 2024
    Let’s say we need to traverse through thousands of files in our S3 Storage in a Ruby app. Let’s say we have a bunch of logs there that we need to read every day and process. If we just use a straightforward approach, like opening, reading, and processing every file one by one, our solution will work, but It will take a lot of time to process. So we need to improve the speed. Here ruby-concurrent gem is our helper https://github.com/ruby-concurrency/concurrent-ruby. Why do we need this gem? Because It’s simpler to use than Threads and this gem has a lot more features in It. In this article, we will use Concurrent::Promises.future as the most common use of concurrent code. Because reading a file from S3 is an IO operation, we can get a huge benefit in speed if we gonna use concurrent code doing HTTP requests. Remember that concurrency will not give you speed improvements if in every Promise or Thread you will do any calculations. Because of Ruby GIL, every thread will be blocked until calculations are finished.
  • Ruby class pattern to work with API requests with built-in async approach
    8 projects | dev.to | 16 May 2024
    concurrent-ruby - to add async requests ability. https://github.com/ruby-concurrency/concurrent-ruby
  • A Tour of Go Examples in Ruby
    1 project | news.ycombinator.com | 16 Mar 2024
  • Exploring concurrent rate limiters, mutexes, semaphores
    2 projects | dev.to | 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!
  • My Adventure with Async Ruby
    1 project | news.ycombinator.com | 3 Sep 2023
    https://github.com/ruby-concurrency/concurrent-ruby has great docs if someone is looking for alternatives.
  • My Adventure With Async Ruby
    1 project | /r/ruby | 23 Jan 2023
    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.
  • Using Concurrent::Promise while rescuing exceptions in Ruby
    2 projects | dev.to | 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 | news.ycombinator.com | 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.

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

  • Intro to Thread-safety in Ruby on Rails
    1 project | /r/ruby | 23 Mar 2022
    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.

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 2024-07-18.
  • Building a Multi-Connection Redis Server with Ruby's Async Library [Part 1]
    1 project | dev.to | 26 Feb 2025
    Recently I've started Codecrafters' Build your own Redis (which I highly recommend!). One of the first steps is to make a TCP server that can accept more than one connection. I noticed that all the provided solutions use threads or IO#Select, and none of them use a fiber-based solution with Async. In this really short article, I'll show how one could achieve the result using Async.
  • Rack for Ruby: Socket Hijacking
    1 project | dev.to | 4 Dec 2024
    Since the threading problem is specific to the Puma web server, let's look at another option: Falcon. This is a new, highly concurrent Rack-compliant web server built on the async gem. It uses Ruby Fibers instead of Threads, which are cheaper to create and have much lower overhead.
  • Persistent Redis Connections in Sidekiq with Async::Redis: A Deep Dive.
    4 projects | dev.to | 18 Jul 2024
    Async is a composable asynchronous I/O framework for Ruby. It allows you to do things concurrently using Fibers. Since 3.0, Ruby has a fiber scheduler and Ruby core supports it. This means you can have non-blocking I/O without much effort, for example, when using Net::HTTP. If you perform a blocking operation, such as an HTTP call, inside a fiber, it will immediately yield so that another fiber can become active and do some useful work instead of blocking and waiting for the HTTP call to complete.
  • 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 | news.ycombinator.com | 1 Sep 2023
    https://github.com/socketry/async 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 | news.ycombinator.com | 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 (https://github.com/socketry/async), 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.
  • How does Ruby handle parallel HTTP requests in separate threads?
    3 projects | /r/ruby | 2 Mar 2023

What are some alternatives?

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

Celluloid - Actor-based concurrent object framework for Ruby

Polyphony - Fine-grained concurrency for Ruby

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

InfluxDB – Built for High-Performance Time Series Workloads
InfluxDB 3 OSS is now GA. Transform, enrich, and act on time series data directly in the database. Automate critical tasks and eliminate the need to move data externally. Download now.
www.influxdata.com
featured
SaaSHub - Software Alternatives and Reviews
SaaSHub helps you find the best software and product alternatives
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the 12th most popular programming language
based on number of references?