Skip to content

Instantly share code, notes, and snippets.

Created July 15, 2021 17:09
What would you like to do?
# Puma can serve each request in a thread from an internal thread pool.
# The `threads` method setting takes two numbers: a minimum and maximum.
# Any libraries that use thread pools should be configured to match
# the maximum value specified for Puma. Default is set to 5 threads for minimum
# and maximum; this matches the default thread size of Active Record.
threads_count = ENV.fetch('RAILS_MAX_THREADS') { 5 }
threads threads_count, threads_count
# Specifies the `port` that Puma will listen on to receive requests; default is 3000.
port ENV.fetch('PORT') { 3000 }
# Specifies the `environment` that Puma will run in.
environment ENV.fetch('RAILS_ENV') { 'development' }
# Specifies the number of `workers` to boot in clustered mode.
# Workers are forked webserver processes. If using threads and workers together
# the concurrency of the application would be max `threads` * `workers`.
# Workers do not work on JRuby or Windows (both of which do not support
# processes).
# workers ENV.fetch("WEB_CONCURRENCY") { 2 }
# Use the `preload_app!` method when specifying a `workers` number.
# This directive tells Puma to first boot the application and load code
# before forking the application. This takes advantage of Copy On Write
# process behavior so workers use less memory. If you use this option
# you need to make sure to reconnect any threads in the `on_worker_boot`
# block.
# preload_app!
# If you are preloading your application and using Active Record, it's
# recommended that you close any connections to the database before workers
# are forked to prevent connection leakage.
before_fork do
ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
# The code in the `on_worker_boot` will be called if you are using
# clustered mode by specifying a number of `workers`. After each worker
# process is booted, this block will be run. If you are using the `preload_app!`
# option, you will want to use this block to reconnect to any threads
# or connections that may have been created at application boot, as Ruby
# cannot share connections between processes.
on_worker_boot do
ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
# Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment