Why does my Ruby program takes different times to execute?-CodePudding

I've just started programming in Ruby. This is my code:

numbers = Array (1..100)
start = Time.now

sum = numbers.inject(0) { |sum, num| sum   num }
puts "sum equals: #{sum}"

time_taken = (Time.now - start) * 1000 * 1000
puts "time taken to execute #{time_taken}"

Why does this code return a different execution time every time I run it?

I mean first time it was:

time taken to execute this: 20.593

second:

time taken to execute this: 27.184

third:

time taken to execute this: 22.516

CodePudding user response：

Why does this code return a different execution time every time I run it?

Because your computer doesn't perform the exact same physical task every time it runs.

Maybe the data happened to be stored in slightly more/less efficient location on the RAM? Maybe your computer was too hot/cold, so performed differently. Maybe you also have 20 StackOverflow tabs open, which was using up system resources :D

Plus, in order to get a more accurate benchmark of how quickly some code runs, you need to decrease the error margin by performing the same operation lots of times.

I would recommend trying the benchmark-ips library if you wish to get some more reliable measurements of your code's performance.