From: Christian Szegedy <szegedy@...>
Date: 2004-11-07T11:18:39+09:00
Subject: Re: Ruby is a slow performer

David G. Andersen wrote:

 > Disabling the GC doesn't help most of the hash-bound benchmarks
 > much if they're written properly.  The basic loop iteration is
 > quite fast if you remove the hash access.  You can draw your own
 > conclusions from this.
 >

Hihi, you are so self-confident. I made some tests, and in fact,
it turned out, that the hash access is not the problem at all:

The original code is:

======================================================
n = (ARGV.shift || 1).to_i

hash = {}
for i in 1..n
     hash['%x' % i] = 1
end

c = 0
n.downto 1 do |i|
     c += 1 if hash.has_key? i.to_s
end

puts c
======================================================

I let it run:

chris@gentoo:~$ time h.rb 500000
real    0m8.929s
user    0m8.724s
sys     0m0.131s

No, I try the decimal conversion instead of the
hexadecimal:

I changed the line
hash['%x' % i] = 1
to
hash['%d' % i] = 1


chris@gentoo:~$ time h.rb 500000
real    0m9.101s
user    0m8.955s
sys     0m0.106s

And the result is roughly the same.
Let's try the functionally equivalent:
hash[i.to_s] = 1

chris@gentoo:~$ time h.rb 500000
real    0m4.673s
user    0m4.600s
sys     0m0.050s

So, in fact the hash access is about the
same speed as in Perl. The slowdown comes from
the formatted output!

So much about the reliability of the shootout!

Best Regards, Christian