What is Ruby Concurrent?

Overview of a Ruby gem designed as a set of concurrency tools
01 September 2017   750

Concurrency is a form of computing in which several computations are executed during overlapping time periods—concurrently—instead of sequentially (one completing before the next starts). This is a property of a system—this may be an individual program, a computer, or a network—and there is a separate execution point or "thread of control" for each computation ("process"). A concurrent system is one where a computation can advance without waiting for all other computations to complete.

Modern concurrency tools include agents, futures, promises, thread pools actors, supervisors etc.Concurrent Ruby makes the strongest thread safety guarantees of any Ruby concurrency library. Every abstraction in this library is thread safe. Similarly, all are deadlock free and many are fully lock free.

Concurrent Ruby is a set of Modern concurrency tools for Ruby. Inspired by Erlang, Clojure, Scala, Haskell, F#, C#, Java, and classic concurrency patterns.

The design goals of this gem are:

  • Be an 'unopinionated' toolbox that provides useful utilities without debating which is better or why
  • Remain free of external gem dependencies
  • Stay true to the spirit of the languages providing inspiration
  • But implement in a way that makes sense for Ruby
  • Keep the semantics as idiomatic Ruby as possible
  • Support features that make sense in Ruby
  • Exclude features that don't make sense in Ruby
  • Be small, lean, and loosely coupled

Concurrency Abstractions

  • Async (Concurrent::Async): A mixin module that provides simple asynchronous behavior to a class, turning it into a simple actor.
  • Future (Concurrent::Future): An asynchronous operation that produces a value. It represents a promise to complete an action at some time in the future.
    • Dataflow: Built on Futures, Dataflow allows you to create a task that will be scheduled when all of its data dependencies are available.
  • Promise (Concurrent::Promise): Similar to Futures, with more features. It represents the eventual value returned from the single completion of an operation.
  • ScheduledTask (Concurrent::ScheduledTask): Like a Future scheduled for a specific future time.
  • TimerTask (Concurrent::TimerTask): A Thread that periodically wakes up to perform work at regular intervals.


gem install concurrent-ruby

or add the following line to Gemfile:

gem 'concurrent-ruby', require: 'concurrent'

and run bundle install from your shell


Everything within this gem can be loaded simply by requiring it:

require 'concurrent'

To use the tools in the Edge gem it must be required separately:

require 'concurrent-edge'

See GitHub for more info.

How To Start an Open Source Project

Personal experience on the open source project; doing it effectively without mistakes
26 January 2018   1293

My name is Dmitriy Strukov and I’m Ruby developer. Today I want to share my experience creating an open source solution. I will talk about what steps the project should take, how to choose the right functionality for the first release, and what mistakes I faced personally when creating my open source project.

Half a year ago, I got the idea that it would be good to create an open source project. Instead of test tasks for the interview, it would be enough for me to send a link to the repository. The prospect of helping colleagues with the solution to their everyday problems inspired me.

I’ve always disliked gems for creating administration panels. Any extra movement needs to redefine the class, and for change fields you need to make changes to the files. After thinking and conversing with colleagues, I decided to create a new library which would be flexible and would not require dashboards or configuration files.


Initially, the project was focused on the Ruby ecosystem, but this would limit the target audience of such a solution. SimpleAdmin is a cross-platform solution for administrative panels, working as a third party service. Obtaining data from the database from the main application works with the help of a plugin. In the Ruby on Rail it engine, in which the necessary endpoints are created. In the near future, the launch of a prototype is planned.

Determine the goals

Every open source project solves a specific problem. Talk with colleagues, chats, forums, and share your idea. It all helps you on the first steps to understand important things, like which solutions already exist, and to hear criticism. Talk with people who already have open source projects. They can give you very valuable advice, so don’t be afraid to ask and take the initiative.

One important bit of advice which I got at that stage is to pay attention in the first place on the documentation of the project. You can have a very good project, but no one will spend the time to understand how it works.

The most important aspect, without which further steps are impossible, is motivation. The idea of the project should inspire you primarily. Most often people get used to the tools with which they work and fall into a comfort zone, so external opinions may be ambiguous.


The choice of a certain task manager is a matter of taste. It should have a clear picture of the tasks and stages of your project.

Divide tasks into sub-tasks. Ideally, if one task does not take more than 3–4 hours, it is important to enjoy the implementation of small tasks. This will help to avoid burnout and loss of motivation.

I use pivotal tracker . The main advantage is a free version for open source projects where you can sort tasks by type (feature, bug, chore, release), and group them into releases and determined deadlines.


Every open source project should contain these things:

  • Open Source license
  • Contributing guidelines
  • Changelog

The README file not only explains how to use your project, but also the purpose of your project. If you do not know how to properly write a README file, you can look at other known open source projects or use a template .

The license guarantees that others can use, copy and modify the source code of the project. You need to add this file to each repository with your open source project. MIT and Apache 2.0 GPLv3 are the most popular licenses for open source projects. If you are not sure what to choose, you can use this convenient service .

The CONTRIBUTING file will help other developers contribute to the project. At the first steps of the project, it is not necessary to pay close attention to this file. You can use the already prepared template from another project.

Changelog contains a supported, chronologically-ordered list of significant changes for each version. As with the CONTRIBUTING file, I do not advise paying special attention to this at an early stage.


To track important changes for users and contributors, there is a semantic version . The version number contains numbers and adheres to the following pattern X.Y.Z.

  • X major release
  • Y minor release
  • Z patch release

Continuous integration / Continuous delivery

To automatically run tests and build, I use Travis CI. It’s also a good idea to add badges to display the successful assembly of the build in the wizard, the test coverage (Codecov), and the documentation (Inch CI).

After each new commit or merge in the master, I automatically have a deploy on Heroku (very convenient integration with GitHub). All tools are absolutely free for an open source project.

My mistakes

To analyze the initial stage, I had an idea, but there was no clear plan. I decided that I wanted to do this without having a clear idea of how much time it would take or a specific representation of the functions that would be in the first version of the library. I had just a lot of desire and lack of a clear plan.

Also, after reading the history of other projects (not only open source), I noticed that at an early stage, some plans are too optimistic. They need a reassessment of their strengths and capabilities. But it’s not easy to find time each day to write a new feature in the project. Most of the tasks eventually had to be weeded out, leaving the necessary minimum for MVP.