From: Josh Cheek <josh.cheek@...>
Date: 2012-02-04T02:43:09+09:00
Subject: Re: Basic Ruby performance

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On Fri, Feb 3, 2012 at 11:13 AM, Dmitry Nikiforov <dniq@dniq-online.com>wrote:

> Robert Klemme wrote in post #1043884:
>
> > Question: the data needs to come from somewhere.  Are you sure that
> > your processing is CPU bound?  If it is IO bound the difference
> > between Perl and Ruby won't really show.  I reckon it's better to
> > create a more realistic example of what you are trying to do and
> > measure again.  (And take care to run tests between Ruby and Perl
> > alternating in order to prevent OS IO caching from preferring one or
> > the other.)
>
> Yep, I'm sure it's CPU bound: the CPU load is at 100%. The data comes in
> faster than the Ruby script can process it, unfortunately, at this
> point. I'm trying to optimize it, of course, but so far Perl version
> beats Ruby hands down. But there aren't too many options at my disposal,
> it seems. In my examples, the "for" seems to be the major culprit: it
> alone, without ANYTHING within the loop, takes 19 seconds to execute 1E8
> times. The (0..1E8).each only saves about 1 second for me. Which doesn't
> really matter - most of the loops in my scripts are "while" loops
> anyway. Still, the regexps themselves run very slow. I wish Ruby used
> standard Perl's PCRE library - that would make at least regexps run as
> fast as they do in Perl, and I would be able to write my scripts in Ruby
> :)
>
> --
> Posted via http://www.ruby-forum.com/.
>
>
It creates a Range, which just iterates, not an array. A more idiomatic way
would probably be (1+10**8).times { ... }

As an aside, if all the processing is happening in the loop, then it might
make more sense that the loop just delegates work out to other processes
(e.g. parse a line or process a parsed set of data). This could be pretty
simple if done with a thread pool in a single Ruby script (you'll want one
of the alternate implementations here since you're CPU bound and MRI has a
GIL), or as arbitrarily complex as you like.

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