What is Ruby Concurrent?

Overview of a Ruby gem designed as a set of concurrency tools
01 September 2017   3149

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.

Git 2.20 to be Available

Let's check updates and features of new version control system
11 December 2018   468

Distributed version control system Git has received another update. In order for Git 2.20 to appear, 83 developers made changes 962 to the zcode. According to the team, this is an order of magnitude higher than the same figure in the largest release of the 2.x.x branch.

The git branch -l command is now a shortened version of the git branch --list - it used to help run reflog during the creation of a new branch. Developers have limited the launch of git fetch: it is only possible with an indication of --force, to avoid problems with consistency when updating the link.

The git help -a and git help -av commands to help newbies display a more verbose output. To return to the old view, just type git help - no-verbose -a. In git send-email, it is possible to extract lines with addresses that end with “-by” from signatures. This is an incompatible change, and it can be disabled by adding to the --suppress-cc = misc-by command.

  • If the repository contains files whose addresses differ only in the case of letters, a warning will be displayed during the execution of git clone.
  • The git format-patch command received the --interdiff and --range-diff options, which in a note or comment list the differences between the existing and previous versions.
  • git mailinfo learned how to recover code patches sent by email with plain text and damaged due to hyphenation.
  • git multi-pack-index now fixes damage in .midx files.
  • Creating experimental commit-graph files for large repositories takes a lot of time, so the developers have provided a form of output about the state of the process.

Performance and Development Support

  • For working builds, the -Wunused-function compilation option is provided.
  • git submodule update is completely rewritten in C.
  • One of the continuous integration (CI) tests, designed to work with the unusual/experimental/random settings, now supports midx and commit-graph files.
  • A new mechanism for finding objects among a large number of pack-files. It relies on combining all .idx files into one.

The previous version of the system was released in September 2018.