unicorn.rb file to deal with dead processes/stale pid and knows about RVM

unicorn.rb

APP_ROOT = File.expand_path(File.dirname(File.dirname(__FILE__)))

if ENV['MY_RUBY_HOME'] && ENV['MY_RUBY_HOME'].include?('rvm')
  begin
    rvm_path = File.dirname(File.dirname(ENV['MY_RUBY_HOME']))
    rvm_lib_path = File.join(rvm_path, 'lib')
    $LOAD_PATH.unshift rvm_lib_path
    require 'rvm'
    RVM.use_from_path! APP_ROOT
  rescue LoadError
    raise "RVM ruby lib is currently unavailable."
  end
end

ENV['BUNDLE_GEMFILE'] = File.expand_path('../Gemfile', File.dirname(__FILE__))
require 'bundler/setup'

worker_processes 4
working_directory APP_ROOT

preload_app true

timeout 30

listen "localhost:8080"
# listen APP_ROOT + "/tmp/sockets/unicorn.sock", :backlog => 64

pid APP_ROOT + "/tmp/pids/unicorn.pid"

stderr_path APP_ROOT + "/log/unicorn.stderr.log"
stdout_path APP_ROOT + "/log/unicorn.stdout.log"

old_pid = APP_ROOT + '/tmp/pids/unicorn.pid'
if File.exists?(old_pid)
  puts "Found existing unicorn PID"
  begin
    pid = File.read(old_pid).to_i
    File.delete(old_pid)
    Process.kill("QUIT", pid)
    puts "shut down previous unicorn (#{pid})"
  rescue Errno::ENOENT, Errno::ESRCH
    puts "was already dead"
  end
end
puts "unicorn started"
before_fork do |server, worker|
  defined?(ActiveRecord::Base) && ActiveRecord::Base.connection.disconnect!
end

after_fork do |server, worker|
  defined?(ActiveRecord::Base) && ActiveRecord::Base.establish_connection
end