memory-tailing-array-test.rb

class Foo
  def large_return
    return mini_return.map { |i| gen_str(i) }
  end

  def large_return_with_freeze
    return mini_return.map { |i| gen_str(i).freeze }
  end

  def mini_return
    return (1...10_000)
  end

  def gen_str(index)
    's' * (100 + index)
  end
end

class FooTest
  def test_method_momery(method)
    before = get_memory_usage
    foo = Foo.new
    100.times do |i|
      foo.send(method).each do |i|
        j = yield(i, foo)
        j.gsub(/s{50}/, '').length == 50 ? '.' : 'x'
      end
    end

    after = get_memory_usage
    puts "Memory: #{(after-before) / 1000}M"
  end

  def test_large_return
    test_method_momery(:large_return) {|i| i }
  end

  def test_large_return_with_freeze
    test_method_momery(:large_return_with_freeze) {|i| i }
  end

  def test_mini_return
    test_method_momery(:mini_return) {|i, foo| foo.gen_str(i) }
  end

  def test_another_large_array
    before = get_memory_usage
    foo = Foo.new
    100.times do |i|
      large_array = foo.mini_return.map{ |i| foo.gen_str(i) }
      large_array.each do |j|
        j.gsub(/s{50}/, '').length == 50 ? '.' : 'x'
      end
    end

    after = get_memory_usage
    puts "Memory: #{(after-before) / 1000}M"
  end

  def get_memory_usage
    `ps -o rss= -p #{Process.pid}`.to_i
  end
end


t = FooTest.new
#t.test_large_return  #=> Memory: 241M
#t.test_mini_return  #=> Memory: 113M
#t.test_another_large_array #=> Memory: 227M
#t.test_large_return_with_freeze #=> Memory: 243M

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