Developers usually feel that ruby is a slow language in terms of time efficiency. This is true but if you use some tricks, your ruby code can run faster. I am giving you some tips (with example) to optimize your ruby code and you can see the results in practice.

How to profile: To know, where to make changes in your code to run faster, you need to profile your code. You can use inbuild “benchmark” library or Ruby-Prof for this purpose. Though there are many other tools, but I found these 2 very suitable and easy to use. Ruby-Prof gives you output in multiple formats so that you can analyze it easily.

Tip #1 :- Printing

Consider following ruby code, how can we make it fast?

require 'benchmark'

n = 50_000

for i in 1..n do
  $stderr.print i, "and"
  $stderr.puts i
end

Above code has a couple of problems, which are making in run slow:
  1. We are using 2 distinct functions calls (puts and print).
  2. We are using ‘puts’, which includes the overhead of adding a ‘\n’ to every line that doesn't already have one.
We can make it fast by, using single print command and by using ‘print’ in place of ‘puts’. Below is the script, which compares the benchmarking result of these 3 approaches.
require 'benchmark'

n = 50_000

Benchmark.bmbm(15) do |r|

  r.report("original version 2 calls") do
      for i in 1..n do
          $stderr.print i, "and"
          $stderr.puts i
      end
  end

  r.report("single puts call") do
      for i in 1..n do
          $stderr.puts "#{i} and #{i}"
      end
  end

  r.report("single print call") do
      for i in 1..n do
          $stderr.print "#{i} and #{i}\n"
      end
  end

end

When I run this script, I found following results from benchmarking:
akash$ ruby puts_print.rb 2> /dev/null
Rehearsal ------------------------------------------------------------
original version 2 calls   0.370000   0.260000   0.630000 (  0.639098)
single puts call           0.250000   0.140000   0.390000 (  0.397769)
single print call          0.170000   0.070000   0.240000 (  0.256804)
--------------------------------------------------- total: 1.260000sec

                             user     system      total        real
original version 2 calls   0.380000   0.270000   0.650000 (  0.658632)
single puts call           0.240000   0.140000   0.380000 (  0.390004)
single print call          0.170000   0.070000   0.240000 (  0.250661)

Above results clearly show an improvement of reducing function calls and of using 'print' over 'puts'.


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