Ruby - Hash#fetch vs #fetch with block performance

ruby_hash_fetch_vs_fetch_block.rb

# Benchmarks time difference between TEST_HASH.fetch(:baz, '') and TEST_HASH.fetch(:baz) { '' }

p 'Key does not exist -----'
TEST_HASH = { foo: :bar }
def operation
  TEST_HASH.fetch(:baz, '')
end

def elaboration_time(&block)
  s = Time.now
  yield
  e = Time.now
  e - s
end

t1 = elaboration_time do
  100.times { operation }
end
p "Time fetch(:baz, ''):", t1

def operation_2
  TEST_HASH.fetch(:baz)  { '' }
end

t2 = elaboration_time do
  100.times { operation_2 }
end

p "Time fetch(:baz){''}:", t2

if t1 < t2
  puts 'fetch missing key WITHOUT block is faster than with a block'
else
  puts 'fetch missing key WITH block is faster than with a block'
end

p 'Key does exist -----'
def operation_3
  TEST_HASH.fetch(:foo)  { '' }
end

t3 = elaboration_time do
  100.times { operation_3 }
end

p "Time fetch(:foo){''}:", t3

def operation_4
  TEST_HASH.fetch(:foo, '')
end

t4 = elaboration_time do
  100.times { operation_4 }
end

p "Time fetch(:foo){''}:", t4
if t3 < t4
  puts 'fetch available key WITH block is faster than without a block'
else
  puts 'fetch avaialable key WITHOUT a block is faster'
end

Hash#fetch performance with and without block

ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-darwin13.0]

• fetch a missing key WITHOUT block is significantly faster than with a block
• fetch available key WITH block is faster than without a block