Hash vs Struct allocations test

gistfile1.rb

# Use with ree.
# http://blog.evanweaver.com/articles/2009/10/21/object-allocations-on-the-web/
GC.enable_stats
def sizeof(obj)
  GC.clear_stats
  obj.clone
  puts "#{GC.num_allocations} allocations"
  GC.clear_stats
  obj.clone
  puts "#{GC.allocated_size} bytes"
end

h = {
  :url           => "http://someurl.com/somewhere/else",
  :proxy_url     => "x" * 120,
  :body_data     => "x" * 120,
  :body_proc     => "x" * 120,
  :header_data   => "x" * 120,
  :header_proc   => "x" * 120,
  :progress_proc => "x" * 120,
  :debug_proc    => "x" * 120,
  :interface_hm  => "x" * 120,
  :userpwd       => "x" * 120,
  :username      => "x" * 120,
  :password      => "x" * 120,
  :proxypwd      => "x" * 120,
  :headers       => ('a'..'z').inject({}) {|h,k| h[k * 10] = k * 100; h},
  :cookies       => "x" * 120,
  :cookiefile    => "x" * 120,
  :cookiejar     => "x" * 120,
  :cert          => "x" * 120,
  :cacert        => "x" * 120,
  :certpassword  => "x" * 120,
  :certtype      => "PEM" * 1024,
  :encoding      => "x" * 120,
  :useragent     => "x" * 120,
  :success_proc  => "x" * 120,
  :failure_proc  => "x" * 120,
  :complete_proc => "x" * 120
}

puts "With an empty Hash instance: "
sizeof(Hash.new);

puts "With a Hash instance, only url and headers: "
sizeof({ :url => "http://someurl.com/somewhere/else", :headers => { :user => "E", :password => "123456788" }});

puts "With a populated Hash instance: "
sizeof(h);

S = Struct.new *h.keys

puts "With an empty Struct instance: "
sizeof(S.new);

s = S.new

h.each do |k,v|
  s.send("#{ k }=", v)
end

puts "With a populated Struct instance: "
sizeof(s);

__END__

With an empty Hash instance:
2 allocations
112 bytes

With a Hash instance, only url and headers:
4 allocations
176 bytes

With a populated Hash instance:
28 allocations
944 bytes

With an empty Struct instance:
1 allocations
208 bytes

With a populated Struct instance:
1 allocations
208 bytes