[Ruby] Benchmark

benchmark.rb

# Benchmark 是一個記錄程式運算時間的 Module 
# 兩個基本指令 :measure, :bm, :bmbm
# 更多：http://www.ruby-doc.org/stdlib-2.0/libdoc/benchmark/rdoc/Benchmark.html#method-c-measure

require 'benchmark'

puts Benchmark.measure{ method_name } 
#     user     system      total        real   <- 不會有這一行
# 1.033333   0.016667   1.016667 (  0.492106)

n = 50000
Benchmark.bm(7) do |x|  # 7 是 label 的寬度
  x.report("for:")   { for i in 1..n; a = "1"; end }  # report()括號內的字串會變成表格的橫列名稱
  x.report("times:") { n.times do   ; a = "1"; end }
  x.report("upto:")  { 1.upto(n) do ; a = "1"; end }
end

#              user     system      total        real
# for:     1.050000   0.000000   1.050000 (  0.503462)
# times:   1.533333   0.016667   1.550000 (  0.735473)
# upto:    1.500000   0.016667   1.516667 (  0.711239)

benchmark_test.rb

require 'benchmark'

@fibo_array = []
def fibonacci(n)
  @fibo_array[n] ||= (n < 2 ? n : fibonacci(n-1)+fibonacci(n-2))
end

def fibonacci2(n)
  def fibo(n)
    prev, curr = 0, 1
    (n-1).times{ curr, prev = prev+curr, curr }
    curr
  end
  n < 2 ? n : fibo(n)
end

Benchmark.bm(7) do |x|
  n = 7000
  x.report("array:") { fibonacci(n) }
  x.report("loop:") { fibonacci2(n) }
end