enable app preload for unicorn

config/unicorn/production.rb

@@ -4,7 +4,7 @@ app_path = "/var/www/danbooru2/current"
 # Set unicorn options
 worker_processes 22
 
-preload_app false
+preload_app true
 timeout 180
 listen "127.0.0.1:9000"
 
@@ -18,7 +18,7 @@ working_directory app_path
 rails_env = ENV['RAILS_ENV'] || 'production'
 
 # Log everything to one file
-stderr_path "/dev/null"
+stderr_path "#{app_path}/log/unicorn.log"
 stdout_path "/dev/null"
 
 # Set master PID location
@@ -26,6 +26,7 @@ pid "#{app_path}/tmp/pids/unicorn.pid"
 
 before_fork do |server, worker|
   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)
@@ -33,8 +34,14 @@ before_fork do |server, worker|
       # someone else did our job for us
     end
   end
+
+  if defined?(ActiveRecord::Base)
+    ActiveRecord::Base.connection.disconnect!
+  end
 end
 
-# after_fork do |server, worker|
-#   ActiveRecord::Base.establish_connection
-# end
+after_fork do |server, worker|
+  if defined?(ActiveRecord::Base)
+    ActiveRecord::Base.establish_connection
+  end
+end