From: Jonathan Simms <slyphon@...>
Date: 2005-12-30T01:51:31+09:00
Subject: Re: What is the difference between :foo and "foo" ?


On Dec 29, 2005, at 12:22 AM, Jim Weirich wrote:

> ara wrote:
>> but this slightly modified version shows strings being a tiny bit
>> faster:
>
> The difference is that your version measures more than just hash  
> access
> speed.  It also includes string and symbol creation times.  In
> particular, to create a symbol, you must first create a string, so you
> have twice as many object creations when using symbols.
>

This version (I believe) shows that by using a string literal, you're
paying for the creation of a string object with each invocation, whereas
by using a symbol, you only pay for the interning once, but on each
subsequent usage, you're using a reference to a singleton.


slyphon@willie ~ $ cat /tmp/bmrk.rb
#!/usr/bin/env ruby

require 'benchmark'

n = 1_000_000
string_hash, symbol_hash = {}, {}


Benchmark.bm(10) do |b|
   b.report("string set"){ n.times{|x| string_hash["foo"] = rand}}
end
Benchmark.bm(10) do |b|
   b.report("symbol set"){ n.times{|x| symbol_hash[:foo] = rand}}
end


slyphon@willie ~ $ ruby /tmp/bmrk.rb
                 user     system      total        real
string set  1.270000   0.000000   1.270000 (  1.274019)
                 user     system      total        real
symbol set  0.880000   0.000000   0.880000 (  0.877080)
slyphon@willie ~ $


- Jonathan Simms