ruby rescue cost

README.md

What/Why

I as concerned about whether the presence of rescue in Ruby had significant performance impact.

In JavaScript for example try/catch historically has had significant impact itself, even when no exceptions were being thrown.

Based on these benchmarks though, I can see Ruby doesn't seem to have significant cost for defining exception handlers.

Results

Calculating -------------------------------------
           exception    136415 i/100ms
               break    138364 i/100ms
              return    137073 i/100ms
-------------------------------------------------
           exception  4168999.4 (±2.5%) i/s -   20871495 in   5.009678s
               break  4300029.8 (±2.8%) i/s -   21584784 in   5.023858s
              return  4173625.1 (±1.8%) i/s -   20972169 in   5.026599s

Credit

Based off of http://blog.honeybadger.io/benchmarking-exceptions-in-ruby-yep-theyre-slow/ , which measures the cost of using exceptions (not my concern- exceptions are rare, I just wanted to know cost of the handler).

rescue.rb

require 'benchmark/ips'

def exit_via_return_with_rescue
  5.times do 
    return
  end
rescue
end

def exit_via_break
  5.times do 
    break
  end
end

def exit_via_return
  5.times do 
    return
  end
end

Benchmark.ips do |x|
  x.report("exception") {  exit_via_return_with_rescue }
  x.report("break") {  exit_via_break }
  x.report("return") {  exit_via_return }
end