# \[ANN\] unicorn 5.0.0 - Rack HTTP server for fast clients and \*nix **URL:** https://rubytalk.org/t/ann-unicorn-5-0-0-rack-http-server-for-fast-clients-and-nix/73291 **Category:** ruby-talk **Created:** [1 November 2015 08:55 UTC](https://rubytalk.org/t/ann-unicorn-5-0-0-rack-http-server-for-fast-clients-and-nix/73291 "2015-11-01T08:55:59Z") **Posts on this page:** 1 **Page:** 1
### Author: ![Eric\_Wong2](https://avatars.discourse-cdn.com/v4/letter/e/b9e5f3/32.png) [@Eric\_Wong2](https://rubytalk.org/u/Eric_Wong2) #### Post date: [1 November 2015 08:55 UTC](https://rubytalk.org/t/ann-unicorn-5-0-0-rack-http-server-for-fast-clients-and-nix/73291/1 "2015-11-01T08:55:59Z")
Unicorn is an HTTP server for Rack applications designed to only serve fast clients on low-latency, high-bandwidth connections and take advantage of features in Unix/Unix-like kernels. Slow clients should only be served by placing a reverse proxy capable of fully buffering both the the request and response in between unicorn and slow clients. \* [http://unicorn.bogomips.org/](http://unicorn.bogomips.org/) \* public list: [unicorn-public@bogomips.org](mailto:unicorn-public@bogomips.org) \* mail archives: [http://bogomips.org/unicorn-public/](http://bogomips.org/unicorn-public/) \* git clone git://bogomips.org/unicorn.git \* [http://unicorn.bogomips.org/NEWS.atom.xml](http://unicorn.bogomips.org/NEWS.atom.xml) \* nntp://news.public-inbox.org/inbox.comp.lang.ruby.unicorn Changes since 4.9.0: unicorn 5.0.0 - most boring major release. EVER. An evolutionary dead-end since its announcement[1] nearly six years ago, this old-fashioned preforker has had enough bugs and missteps that it's managed to hit version 5! I wish I could say unicorn 5 is leaps and bounds better than 4, but it is not. This major version change allows us to drop some cruft and unused features which accumulated over the years, resulting in several kilobytes of memory saved[2]! Compatibility: \* The horrible, proprietary (:P) "Status:" response header is   finally gone, saving at least 16 precious bytes in every HTTP   response. This should make it easier to write custom HTTP clients   which are compatible across all HTTP servers. It will hopefully   make migrating between different Rack servers easier for new   projects. \* Ruby 1.8 support removed. Ruby 1.9.3 is currently the earliest   supported version. However, expect minor, likely-unnoticeable   performance regressions if you use Ruby 2.1 or earlier. Going   forward, unicorn will favor the latest version (currently 2.2) of   the mainline Ruby implementation, potentially sacrificing   performance on older Rubies. \* Some internal, undocumented features and APIs used by   derivative servers are gone; removing bloat and slightly lowering   memory use. We have never and will never endorse the use of any   applications or middleware with a dependency on unicorn,   applications should be written for Rack instead.   Note: Rainbows! 5.0 will be released next week or so to be   compatible with unicorn 5.x New features: \* sd\_listen\_fds(3) emulation added for systemd compatibility.   You may now stop using PID files and other process monitoring   software when using systemd. > **ยทยทยท** > > -- > EW