Found an article Passenger (mod_rails) for development. Now with debugger!. Like it - I use debugger a lot. Added some automation to start rdebug

lib/tasks/adhoc/restart.rake

namespace :phusion do
  desc 'Restart phusion'
  task :restart do
    system("touch tmp/restart.txt")
    if ENV["DEBUG"] == 'true'
      system("touch tmp/debug.txt")
      attach_debugger
    end
  end
end

def attach_debugger
  if RUBY_PLATFORM =~ /linux/
    shell_helper = File.join(RAILS_ROOT,'lib','tasks','adhoc','attach_debugger.sh')
    if ENV['DISPLAY']
      system("xterm -e '#{shell_helper}'")
      system("touch tmp/restart.txt")
    else
      exec shell_helper
    end
  end
end

lib/tasks/adhoc/attach_debugger.sh

#!/bin/sh
while true; do
rdebug -c 2>/dev/null
if [ "$?" == "0" ]; then
  break
fi
sleep 1
done