mem_test.rb

#!/usr/bin/env ruby
 
def mem_usage
  `ps -o rss= -p #{$$}`.to_i
end
 
count = (ARGV[0] || 5).to_i

puts "current process id is #{$$}" 
puts "Memory before anything: #{mem_usage}"

a = []
b = []
1000000.times { |n| a << n}
500000.times { |n| b << n}

puts "Memory before process: #{mem_usage}"
count.times do |n|
  puts "Memory before process number #{n}: #{mem_usage}"
  a - b
  puts "Memory after process number #{n}: #{mem_usage}"

end
a = nil
b = nil
GC.start
puts "Memory on complete: #{mem_usage}"

results.txt

current process id is 14552
Memory before anything: 1316
Memory before process: 7240
Memory before process number 0: 7240
Memory after process number 0: 17644
Memory before process number 1: 17644
Memory after process number 1: 25596
Memory before process number 2: 25596
Memory after process number 2: 25596
Memory before process number 3: 25596
Memory after process number 3: 25596
Memory before process number 4: 25596
Memory after process number 4: 25596
Memory on complete: 25080