From: Stefan Matthias Aust <sma@3plus4.de>
Date: 2001-05-26T18:10:05+09:00
Subject: [ruby-talk:15747] Re: java based interpreter and regexes

Sean Russell <ser@germane-software.com> wrote:

>I wrote a little benchmark to test Ruby vs. org.apache.regexp.

I compared Ruby 1.6.4 against JDK 1.4 beta and cannot confirm your
results.  (1.4 includes a regex package which looks like the one from
the jakarata project so I used the built-in version)

My ruby code needs some 4.7s to run (I used cygwin's time command)
My java code needs some 2.7s to run (again measured with time)

However, the time command also includes the time needed to initialize
and start the VM, so I added code just to benchmark the 10000
RE-calls.  

Then, the ruby code still needs 4.3s but the Java code only 1.9s.

So don't worry about the speed of the regexp code.  I also doubt that
this would be the most difficult part for a Ruby interpreter written
in Java.  To get it compatible with all "features" of the C one is
much more challenging IMHO.

>So Ruby is about 2.5 times faster.  Not suprising, considering that regular 
>expressions in Ruby are handled by native code.  I don't think the Java lib 
>is too slow.

JIT-compiled code is typically faster than you'd expect.  I don't want
to go into details, but a sophisticated compiler like the SELF VM
which was the precursor of the Hotspot VM is able to generate faster
code than a static compiler can because its ability to dynamically
recompile code based on type heuristics generated while the program is
running.

bye

PS: Here's what I changed:

...
import java.util.regex.*;
...
  Pattern regexpr = Pattern.compile(_re[regnum]);
...
    regexpr.matcher( _str[strnum] ).matches();
...
-- 
Stefan Matthias Aust \/ Truth Until Paradox