memory_monitor.rb

#!/usr/bin/env ruby

require 'net/smtp'
require 'socket'

class MemoryMonitor
  def bloated_processes
    # the '$11 $12 $13 $14 $15 $16' thing is an ignorant solution for something like '$11 *'
    # 'grep -v packet_worker_runner' ignores backgroundrb
    `ps auwx | grep -v packet_worker_runner | awk '{ if ($6 > 500000) print $2 "##" $6 "##" $11,$12,$13,$14,$15,$16}'`
  end

  def kill_bloated_processes
    bloated_processes.each do |p|
      pid, size, proctitle = p.split("##")
      next if proctitle.include?("COMMAND")

      Process.kill(9, pid)  

      message = <<-MESSAGE
Subject: Runaway process on #{Socket.gethostname}

#{proctitle}
Size: #{size.to_i / 1024}MB
      MESSAGE

      smtp = Net::SMTP.new('smtp.gmail.com', 587)
      smtp.enable_starttls
      smtp.start('smtp.gmail.com', 'happyrobot@example.com', 'password', :plain)
      smtp.send_message message, 'happyrobot@example.com', 'developers@example.com'
      smtp.finish
    end
  end
end

MemoryMonitor.new.kill_bloated_processes