Benchmark while vs each_with_index. RE: https://github.com/rails/rails/pull/12065

while-vs-each_with_index.rb

require 'benchmark/ips'

ARRAY = [1,2,3,1,'2',4,'5',6,7,8,9,'10']

Benchmark.ips do |x|
  x.report("while") {
    hash   = {}
    index  = 0
    length = ARRAY.length

    while index < length
      hash[index] = ARRAY[index]
      index += 1
    end

    hash
  }

  x.report("each_with_index") {
    hash   = {}

    ARRAY.each_with_index do |item, index|
      hash[index] = item
    end

    hash
  }
end

=begin
Calculating -------------------------------------
               while     25622 i/100ms
     each_with_index     18032 i/100ms
-------------------------------------------------
               while   333404.8 (±16.7%) i/s -    1178612 in   5.521999s
     each_with_index   208629.7 (±15.4%) i/s -    1009792 in   5.001059s

real  0m16.952s
user  0m15.690s
sys 0m1.194s
=end