Unicorn + Heroku + worker_killer + GC vars tweak

config.ru

# This file is used by Rack-based servers to start the application.

# GC_FREQUENCY = 8
# require "unicorn/oob_gc"
# GC.disable # Don't run GC during requests
# use Unicorn::OobGC, GC_FREQUENCY # Only GC once every GC_FREQUENCY requests

# # Unicorn self-process killer
require "unicorn/worker_killer"

# # Max memory size (RSS) per worker
use Unicorn::WorkerKiller::Oom, (170*(1024**2)), (180*(1024**2))

require ::File.expand_path("../config/environment",  __FILE__)

# remaining lines omitted

unicorn.rb

worker_processes Integer(ENV["WEB_CONCURRENCY"] || 3)
timeout Integer(ENV["UNICORN_TIMEOUT"] || 30)

preload_app true

listen ENV["PORT"], :backlog => Integer(ENV["UNICORN_BACKLOG"] || 1)

before_exec do |server|
  ENV["RUBY_HEAP_MIN_SLOTS"]=800000
  ENV["RUBY_GC_MALLOC_LIMIT"]=59000000
  ENV["RUBY_HEAP_SLOTS_INCREMENT"]=10000
  ENV["RUBY_HEAP_SLOTS_GROWTH_FACTOR"]=1
  ENV["RUBY_HEAP_FREE_MIN"]=100000
end

before_fork do |server, worker|
  Signal.trap "TERM" do
    puts "Unicorn master intercepting TERM and sending myself QUIT instead"
    Process.kill "QUIT", Process.pid
  end

  defined?(ActiveRecord::Base) and
    ActiveRecord::Base.connection.disconnect!

  defined?(Resque) and
      Resque.redis.quit
end

after_fork do |server, worker|
  Signal.trap "TERM" do
    puts "Unicorn worker intercepting TERM and doing nothing. Wait for master to send QUIT"
  end

  if defined?(ActiveRecord::Base)
    config = Rails.application.config.database_configuration[Rails.env]
    config["reaping_frequency"] = ENV["DB_REAP_FREQ"] || 10 # seconds
    config["pool"]              = ENV["DB_POOL"] || 6
    ActiveRecord::Base.establish_connection(config)
  end

  defined?(Resque) and
      Resque.redis = ENV["REDISTOGO_URL"]
end