Ruby thread to monitor ruby processes and stop them should they reach a certain memory size

unicorn_reaper.rb

# This file can be required from "config/unicorn.rb" so the thread will run alongside the master process
# This will kill any rogue memory-greedy unicorn processes
unicorn_worker_memory_limit = 220_000

Thread.new do
  loop do
    begin
      lines = `ps -e -www -o pid,rss,command | grep '[u]nicorn_rails worker'`.split("\n")
      lines.each do |line|
        parts = line.split(' ')
        if parts[1].to_i > unicorn_worker_memory_limit
          # tell the worker to die after it finishes serving its request
          ::Process.kill('QUIT', parts[0].to_i)
        end
      end
    rescue Object
      # don't die ever once we've tested this
      nil
    end
    sleep 60 * 50
  end
end

See https://github.com/ridiculous/signals for an example of trapping signals to hot-reload some code