Bug, probably related to Unicoen

[Felix Yasnopolski <felix.yasnopolski@gmail.com>]

We use Ruby v2.2.3, Rails v4.2.4, Unicorn v5.1.0 in production.

ActiveRecord validation rules and callbacks for all models of app has
been disabled after unicorn restart (from log rotation script). Here
it is

/var/www/fitness_crm/shared/log/production.log
/var/www/fitness_crm/shared/log/unicorn.stderr.log
/var/www/fitness_crm/shared/log/unicorn.stdout.log {
        daily
        missingok
        rotate 30
        compress
        notifempty
        create 640 deploy deploy
        sharedscripts
        postrotate
                kill -s USR2 `cat
/var/www/fitness_crm/shared/tmp/pids/unicorn.pid`
        endscript
}

We've changed the script to send USR1 instead of USR2, but nothing has
changed. When USR1 is sent validations/callbacks simply keep being
disabled. Here is our unicorn configuration file

working_directory "/var/www/fitness_crm/current"
pid "/var/www/fitness_crm/shared/tmp/pids/unicorn.pid"
stdout_path "/var/www/fitness_crm/shared/log/unicorn.stdout.log"
stderr_path "/var/www/fitness_crm/shared/log/unicorn.stderr.log"

listen "/tmp/unicorn.fitness_crm_production.sock"

worker_processes 8
timeout 30

preload_app true

before_exec do |server|
  ENV["BUNDLE_GEMFILE"] = "/var/www/fitness_crm/current/Gemfile"
end

before_fork do |server, worker|
  # Disconnect since the database connection will not carry over
  if defined? ActiveRecord::Base
    ActiveRecord::Base.connection.disconnect!
  end

  # Quit the old unicorn process
  old_pid = "#{server.config[:pid]}.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # someone else did our job for us
    end
  end

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

  sleep 1
end

after_fork do |server, worker|
  # Start up the database connection again in the worker
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.establish_connection
  end

  if defined?(Resque)
    Resque.redis = 'localhost:6379'
  end
end

After this we kill unicorn and start it manually with command:

bundle exec unicorn -D -c
/var/www/fitness_crm/shared/config/unicorn.rb -E production

After this everything is good and validations and callbacks are
enabled again. Please, help to find out what is the reason of such a
behavior and how to fix it.