Rails script benchmarking

bench_rails_script_memory_usage.rb

def start_script
  puts "starting script..."
  # Remove the X to enable the parameters for tuning.
  # These are the default values as of Ruby 2.2.0.
  @child = spawn(<<-EOC.split.join(" "))
    XRUBY_GC_HEAP_FREE_SLOTS=4096
    XRUBY_GC_HEAP_INIT_SLOTS=10000
    XRUBY_GC_HEAP_GROWTH_FACTOR=1.8
    XRUBY_GC_HEAP_GROWTH_MAX_SLOTS=0
    XRUBY_GC_HEAP_OLDOBJECT_LIMIT_FACTOR=2.0
    XRUBY_GC_MALLOC_LIMIT=16777216
    XRUBY_GC_MALLOC_LIMIT_MAX=33554432
    XRUBY_GC_MALLOC_LIMIT_GROWTH_FACTOR=1.4
    XRUBY_GC_OLDMALLOC_LIMIT=16777216
    XRUBY_GC_OLDMALLOC_LIMIT_MAX=134217728
    XRUBY_GC_OLDMALLOC_LIMIT_GROWTH_FACTOR=1.2
    rails runner scripts/rbup.rb & echo $! >> tmp/pids/rbup.pid
  EOC
  sleep 0.1 until alive?
end

def alive?
  lines = `ps -p #{server_pid} | wc -l`.to_i
  lines == 2
end

def stop_script
  puts "stoping script..."
  Process.kill :KILL, server_pid if server_pid && alive?
  Process.wait @child
  delete_pid
end

def delete_pid
  `if test -f tmp/pids/rbup.pid; then rm tmp/pids/rbup.pid; fi`
end

def server_pid
  `cat tmp/pids/rbup.pid`.to_i
end

def memory_size_mb
  (`ps -o rss= -p #{server_pid}`.to_i * 1024).to_f / 2**20
end


stop_script if @child

start_script
seconds = 0
used_mb = 0
max_mem = 0
while alive?
  used_mb = memory_size_mb
  max_mem = [max_mem, used_mb].max
  puts "#{seconds}sec - #{'%.2f' % used_mb.round} MB"
  seconds += 1
  sleep 1
end

stop_script

puts "Total Time: #{seconds}sec"
puts "Max Memory: #{'%.2f' % max_mem} MB"