A pattern for measuring memory use of a block of code

[jjb]

What do you think of this pattern for measuring memory use of a block of code? Assume:

• single-threaded process, so the block of code is the only thing doing work
• the code is known to last 10+ seconds

require 'get_process_mem'

GPM = GetProcessMem.new

def measure_memory_use
  start = GPM.bytes
  samples = []
  shutdown = false

  t = Thread.new do
    loop do
      break if shutdown
      sleep 0.1
      samples << GPM.bytes
    end
  end

  yield

  shutdown=true
  samples.max - start
end

class MyClass
  def initialize(x)
    @x = x
  end
end

puts "warmup"
a = []
20_000_000.times{a<<MyClass.new(rand)}
a=nil
puts

#3.times{GC.start}
#GC.compact

Process.warmup

puts "1 million"
puts measure_memory_use{ a=[]; 1_000_000.times{a<<MyClass.new(rand)}; sleep 1 }

Process.warmup

puts "2 million"
puts measure_memory_use{ a=[]; 2_000_000.times{a<<MyClass.new(rand)}; sleep 1 }

➔ ruby code.rb
warmup

1 million
48316416
2 million
96649216