pitchfork: Rack HTTP server for shared-nothing architecture
pitchfork is a preforking HTTP server for Rack applications designed
to minimize memory usage by maximizing Copy-on-Write performance.
unicorn (of which
pitchfork is a derivative), it is 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 request and response in between
pitchfork and slow clients.
Shared-Nothing architecture: workers all run within their own isolated address space and only serve one client at a time for maximum performance and robustness. Concurrent requests don't need to compete for the GVL, or impact each others latency when triggering garbage collection. It also does not care if your application is thread-safe or not.
pitchforkcan be configured to periodically promote a warmed up worker as the new template from which workers are forked. This dramatically improves the proportion of shared memory, making processes use only marginally more memory than threads would.
Compatible with Ruby 2.5.0 and later.
pitchforkwill reap and restart workers that die from broken apps. There is no need to manage multiple processes or ports yourself.
pitchforkcan spawn and manage any number of worker processes you choose to scale to your backend.
Adaptative timeout: request timeout can be extended dynamically on a per request basis, which allows to keep a strict overall timeout for most endpoints, but allow a few endpoints to take longer.
Load balancing is done entirely by the operating system kernel. Requests never pile up behind a busy worker process.
When to Use
Pitchfork isn't inherently better than other Ruby application servers, it mostly focus on different tradeoffs.
If you are fine with your current server, it's best to stick with it.
If there is a problem you are trying to solve, please read the migration guide first.
Ruby(MRI) Version 2.5 and above.
pitchfork can be used on any Unix-like system, however the reforking
PR_SET_CHILD_SUBREAPER which is a Linux 3.4 (May 2012) feature.
Add this line to your application's Gemfile:
And then execute:
$ bundle install
Or install it yourself as:
$ gem install pitchfork
In your application root directory, run:
$ bundle exec pitchfork
pitchfork will bind to all interfaces on TCP port 8080 by default.
You may use the
--listen switch to bind to a different
address:port or a UNIX socket.
pitchfork will look for the config.ru file used by rackup in APP_ROOT.
For deployments, it can use a config file for pitchfork-specific options
specified by the
--config-file/-c command-line switch.
See the configuration documentation for the syntax
of the pitchfork-specific options.
The default settings are designed for maximum out-of-the-box compatibility with existing applications.
Most command-line options for other Rack applications (above) are also
pitchfork -h to see command-line options.
Relation to Unicorn
Pitchfork initially started as a Unicorn patch, however some of Unicorn features as well as Unicorn policy of supporting extremely old Ruby version made it challenging.
Forking was the occasion to significantly reduce the complexity.
However some large parts of Pitchfork like the HTTP parser are still mostly unchanged from Unicorn, and Unicorn is fairly stable these days. As such we aim to backport any Unicorn patches that may apply to Pitchfork and vice versa.
pitchfork is copyright 2022 Shopify Inc and all contributors. It is based on Unicorn 6.1.0.
Unicorn is copyright 2009-2018 by all contributors (see logs in git). It is based on Mongrel 1.1.5. Mongrel is copyright 2007 Zed A. Shaw and contributors.
pitchfork is licensed under the GPLv2 or later or Ruby (1.8)-specific terms. See the included LICENSE file for details.
Thanks to Eric Wong and all Unicorn and Mongrel contributors over the years. Pitchfork would have been much harder to implement otherwise.
Thanks to Will Jordan who implemented Puma's "fork worker" experimental feature which have been a significant inspiration for Pitchfork.
Thanks to Peter Bui for letting us use the
pitchfork name on Rubygems.