Memory usage monitor

memory_usage_monitor.rb

# Usage:
# 
# peak_memory = track_memory do
#   1000000.times { |i| puts i }  
# end
# 
# puts peak_memory
#  -> 845073 

require 'thread'

class MemoryUsageMonitor
  attr_reader :peak_memory

  def initialize(frequency= 0.001)
    @frequency = frequency
    @peak_memory = 0
  end

  def start
    @thread = Thread.new do
      while true do
        memory = `ps -o rss -p #{Process::pid}`.chomp.split("\n").last.strip.to_i
        @peak_memory = [memory, @peak_memory].max
        sleep @frequency
      end
    end
  end

  def stop
    Thread.kill(@thread)
  end

  def self.voice
    0 # may be calculated default memory usage of system
  end

  def peak_memory
    @peak_memory - MemoryUsageMonitor.voice
  end
end


module Kernel

  def track_memory(&block)
    mm = MemoryUsageMonitor.new
    mm.start
    yield
    mm.stop
    mm.peak_memory
  end

end