From: kryglik <kryglik@...>
Date: 2006-01-02T21:42:58+09:00
Subject: Re: strange speeds

Robert Klemme wrote:
> kryglik <kryglik@iol.cz> wrote:
>> Hello ruby people,
>>  I've tried to make some speed test in ruby to find out how fast is
>> searching in hash (using has_key?)
>>
>> The results were OK but I discovered curious thing -- when i generate
>> big hash the speed is different when i unserialize (marshal.load) the
>> same hash.
>>
>> Unserialized Hash is 1.5x faster in has_key? method. Tried it with
>> GC.disable as well, results were same.
>>
>> What am I missing?
>>
>> Thanx for any ideas
> 
> The first reason that comes to mind is different insertion order. But I 
> hardly believe it could make such a big difference.  Care to post your 
> testing code?
> 
> Kind regards
> 
>    robert
> 

Well, insertion order will be same, won't be?

h = {}
h_slovo = []

if not true  #HERE YOU SWITCH IF GENERATE/LOAD
     for x in 1..40_000
         if x % 2000  == 0
             puts x
         end

         slovo = ""

         for z in 1..32
             slovo += (rand(25)+65).chr
         end

         if rand(10) == 3
             h_slovo << slovo
         end

         h.update slovo => rand(1_000_000)
         slovo = nil
     end

     f = File.new("hash.marshal","w+")
     f.puts(Marshal.dump(h))
     f.close

     f = File.new("hash1.marshal","w+")
     f.puts(Marshal.dump(h_slovo))
     f.close
else

     puts "loading hash"
     h = Marshal.load(File.open("hash.marshal","r"))
     puts "loading hash1"
     h_slovo = Marshal.load(File.open("hash1.marshal","r"))
     puts "done"
end

t1 = Time.now

for slovo1 in h_slovo
h.has_key? h_slovo
end

t2 = Time.now

puts "hash: " + h.size.to_s
puts "hled: " + h_slovo.size.to_s
puts t2-t1