map_block_vs_magic.rb

require 'benchmark'

puts `uname -a`
puts `ruby --version`
puts '-' * 78

@small = (0 ..   10).to_a
@exps  = []
GC.enable_stats

def with_gc
  alloc = ObjectSpace.allocated_objects

  GC.clear_stats
  yield
  alloc = ObjectSpace.allocated_objects - alloc
  puts "  times gc'ed: #{GC.collections}"
  puts "  allocated..: #{alloc}"
  [ GC.collections, alloc ]
end

puts "--"
puts "map with block vs &: -- iterations by powers of 10"
puts '#' * 78
Benchmark.bm do |x|
  (0...6).each do |exp|
    puts "## 10^#{exp}"
    stat1 = with_gc { x.report("simply-S") { (10**exp).times { @small.map  {|s| s.to_s } } } }
    stat2 = with_gc { x.report("cutesy-S") { (10**exp).times { @small.map  &:to_s        } } }
    puts "   Δ garbage (simple-cutesy): #{stat1[0] - stat2[0]}"
    puts "   Δ alloced (simple-cutesy): #{stat1[1] - stat2[1]}"
    puts '-----'
  end
end

puts
puts "map with block vs &: -- data size by powers of 10"
puts '*' * 78
@exps = (0..6).map{ |exp| ( 0 ... (10**exp) ).to_a }

Benchmark.bm do |x|
  @exps.each_with_index do |ary, exp|
    puts "## 10^#{exp} #{ary.class} #{ary.size}"
    stat1 = with_gc { x.report('simply') { ary.map  {|s| s.to_s } } }
    stat2 = with_gc { x.report('cutesy') { ary.map  &:to_s        } }
    puts "  Δ garbage (simple-cutesy): #{stat1[0] - stat2[0]}"
    puts "  Δ alloced (simple-cutesy): #{stat1[1] - stat2[1]}"
    puts '-----'
  end
end