Profiling Ruby Code

To really drill into your code try out stackprof.

Here’s a quick solution on how to use it:
Install the gem: gem install stackprof. In your code add: require 'stackprof' and surround the part that you want to check with this:

StackProf.run(mode: :cpu, out: 'stackprof-output.dump') do
{YOUR_CODE}
end


After running your ruby script go check the output in the terminal with stackprof stackprof.dump:

Mode: cpu(1000)
Samples: 9145 (1.25% miss rate)
GC: 448 (4.90%)

 TOTAL    (pct)     SAMPLES    (pct)     FRAME
   236   (2.6%)         231   (2.5%)     String#blank?
   546   (6.0%)         216   (2.4%)     ActiveRecord::ConnectionAdapters::Mysql2Adapter#select
   212   (2.3%)         199   (2.2%)     Mysql2::Client#query_with_timing
   190   (2.1%)         155   (1.7%)     ERB::Util#html_escape``

Here you can see all your methods that require a lot of time. Now the awesome part: To drill in just do stackprof stackprof.dump --method String#blank? and you get the output for the specific method:

String#blank? (lib/active_support/core_ext/object/blank.rb:80)
  samples:   231 self (2.5%)  /    236 total (2.6%)
  callers:
    112  (   47.5%)  Object#present?
  code:
                                  |    80  |   def blank?
  187    (2.0%) /   187   (2.0%)  |    81  |     self !~ /[^[:space:]]/
                                  |    82  |   end

And you can quite easily figure out which part of your code takes a lot of time to run.

If you want to get a visual output do stackprof stackprof.dump --graphviz >> stackprof.dot and using graphviz (brew install graphviz) dot -T pdf -o stackprof.pdf stackprof.dot get a beautiful PDF output, which highlights the methods that take a long time to run.