Using ruby-prof to get runtime difference between "1+1" and "1x2"

Question

Attempting to profile the difference in runtime between "1+1" and "1x2" using Ruby and the gem ruby-prof.

Install the gem and hacked together some code that appears to work, but does not give me the answer I'm looking for, that being the difference in runtime.

Is this possible, and if so, what code would give me this answer.

---

This code appears to work, but does not allow me to see a runtime difference.

---

require 'ruby-prof'

result = RubyProf.profile do
1+1
end
printer = RubyProf::GraphPrinter.new(result)

result = RubyProf.profile do
1x2
end
printer = RubyProf::GraphPrinter.new(result)

---

Which returns this in IRB

---

irb(main):001:0> require 'ruby-prof'
=> true
irb(main):002:0>
irb(main):003:0* result = RubyProf.profile do
irb(main):004:1* 1+1
irb(main):005:1> end
=> #<RubyProf::Result:0x11050c8>
irb(main):006:0> printer = RubyProf::GraphPrinter.new(result)
=> #<RubyProf::GraphPrinter:0x1332c18 @result=#<RubyProf::Result:0x11050c8>, @ou
tput=nil, @options={}, @thread_times={6793716=>0.01}>
irb(main):007:0>
irb(main):008:0* result = RubyProf.profile do
irb(main):009:1* 1x2
irb(main):010:1> end
SyntaxError: (irb):9: syntax error, unexpected tIDENTIFIER, expecting keyword_en
d
        from C:/Ruby193/bin/irb:12:in `<main>'
irb(main):011:0> printer = RubyProf::GraphPrinter.new(result)
=> #<RubyProf::GraphPrinter:0x1124310 @result=#<RubyProf::Result:0x11050c8>, @ou
tput=nil, @options={}, @thread_times={6793716=>0.01}>
irb(main):012:0>

Answer 1

1x2 means nothing in ruby. Use 1*2 instead.

EDIT: You must run the code more times as it is too fast to measure.

require 'ruby-prof'

prof1 = RubyProf.profile do
  10_000_000.times {1+1}
end

prof2 = RubyProf.profile do
  10_000_000.times {1*2}
end

RubyProf::GraphPrinter.new(prof1).print
RubyProf::GraphPrinter.new(prof2).print

Anyway I think the best way to do it is with Benchmark:

require 'benchmark'

Benchmark.bm do |x|
  x.report("1+1") {15_000_000.times {1+1}}
  x.report("1*2") {15_000_000.times {1*2}}
end

It gives me:

         user     system      total        real
1+1  2.386000   0.000000   2.386000 (  2.392529)
1*2  2.403000   0.000000   2.403000 (  2.413323)

Multiplication is just a bit slower. But the difference is too small to mean anything.

Answer 2

Multiplication is done with * not with x. This is why you get the syntax error on your second example.

Answer 3

You want to use 1 * 2, not 1x2...

If any case, you won't get any noticeable difference. You will be measuring the time it takes Ruby to make a method call, as the operation itself will take negligible time compared to that.

Answer 4

Ruby prof only seems to give you time in 100th of seconds. These operations are faster than that and thus both operations will give you the same result.

require 'ruby-prof'
result = RubyProf.profile do
  1 + 1
end
printer = RubyProf::GraphPrinter.new(result)
printer.print(STDOUT)
result = RubyProf.profile do
  1 * 2
end
printer = RubyProf::GraphPrinter.new(result)
printer.print(STDOUT)

Gives :

Thread ID: 70218521201980
Total Time: 0.01

  %total   %self     total      self      wait     child            calls   Name
--------------------------------------------------------------------------------
 100.00% 100.00%      0.00      0.00      0.00      0.00                1     Global#[No method]


Thread ID: 70218521201980
Total Time: 0.01

  %total   %self     total      self      wait     child            calls   Name
--------------------------------------------------------------------------------
 100.00% 100.00%      0.00      0.00      0.00      0.00                1     Global#[No method]

Which is the same time. Perhaps using the built in Time you could get a better result. This gives the time in milliseconds :

  start = Time.now
  1 + 1
  puts (Time.now - start) * 1000


  start = Time.now
  1 * 2
  puts (Time.now - start) * 1000

They both average out to be the same. ie 1000th of a millisecond