Unicorn is a

Rack Rack or racks may refer to: Storage and installation * Amp rack, short for amplifier rack, a piece of furniture in which amplifiers are mounted * Bicycle rack, a frame for storing bicycles when not in use * Bustle rack, a type of storage bin m ...

HTTP server An HTTP server is a computer (software) program (or even a software component included in an other program) that plays the role of a server in a client–server model by implementing the ''server part'' of the HTTP and/or HTTPS network proto ...

to serve

Ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapp ...

web application A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serve ...

s on UNIX environment. It is optimised to be used with

nginx Nginx (pronounced "engine x" ) is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. The software was created by Igor Sysoev and publicly released in 2004. Nginx is free and open-source software ...

. It is based on now deprecated

Mongrel A mongrel, mutt or mixed-breed dog is a dog that does not belong to one officially recognized breed and including those that are the result of intentional breeding. Although the term ''mixed-breed dog'' is sometimes preferred, many mong ...

1.1.5 from 2008.

Architecture

Unicorn uses a master/worker architecture, where a master process forks worker processes and controls them. The application runs in a single thread.

Reception and use

Unicorn was considered as “one of the most popular servers for

Rails Rail or rails may refer to: Rail transport *Rail transport and related matters * Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ...

”.

Twitter Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and ...

started to test Unicorn in 2010. This server is shipped with

Discourse Discourse is a generalization of the notion of a conversation to any form of communication. Discourse is a major topic in social theory, with work spanning fields such as sociology, anthropology, continental philosophy, and discourse analysis. ...

. Their system administrator Sam Saffron noted Unicorn was reliable, as it reaps unresponsive workers. Unicorn inspired other projects like

Gunicorn The Gunicorn "Green Unicorn" (pronounced jee-unicorn or gun-i-corn) is a Python Web Server Gateway Interface (WSGI) HTTP server. It is a pre-fork worker model, ported from Ruby's Unicorn project. The Gunicorn server is broadly compatible with a ...

, a fork to run Python applications. As of 2018, projects tend to favour Puma. The

Heroku Heroku is a cloud platform as a service (PaaS) supporting several programming languages. One of the first cloud platforms, Heroku has been in development since June 2007, when it supported only the Ruby programming language, but now supports Java, ...

hosting provider recommends since 2015 to migrate from Unicorn to Puma.

Deliveroo Deliveroo is a British online food delivery company founded by Will Shu and Greg Orlowski in 2013 in London, England. It operates in the United Kingdom, France, Belgium, Ireland, Italy, Singapore, Hong Kong, the United Arab Emirates and Kuwait ...

published a benchmark comparing the two servers and concluded “Puma performs better than Unicorn in all tests that were either heavily IO-bound or that interleaved IO and CPU work”, but that Unicorn was still slightly better performing in pure CPU situations.

GitLab GitLab Inc. is an open-core company that operates GitLab, a DevOps software package which can develop, secure, and operate software. The open source software project was created by Ukrainian developer Dmitriy Zaporozhets and Dutch developer ...

switched to Puma from Unicorn in 2020.

References

External links

* {{Web server software Free web server software Free software programmed in Ruby Web server software for Linux