From: sa 125 <s_ayalon@...>
Date: 2008-11-27T22:37:08+09:00
Subject: Performance issues with large files -- ruby vs. python :)

Hi all -

I'm new to ruby after working with python for a while. My work is
performing data mining and doing some web dev for my company. We
recently started looking at rails, and I wanted to see if it's worth
migrating some of my code from python to ruby. So much for the intro.

I've re-written a script that extracts data from a very large csv file
(~8 million rows or so, almost 1Gb in size). It does so by iterating
through the rows and building a tree-like hash (dict in python) in
memory that will later be written to our DB. The structure is something
like this:

{date =>
  { company =>
     { product => [array of relevant info] } } }

This way I only get the data I need, sort it on the fly, and speed up
the process. The idea is to propagate down the keys if some field has
duplicate values -- I hope that makes some sense.. Anyway, I copied my
python code, and basically translated it to ruby.

This is where it got interesting -- after solving all the quirks and
getting it to run, it appeared to be super slow compared to python. I
mean nearly an 30 min in ruby vs under 2 minutes in python code. It's
worth mentioning that I used the psyco module in python, and that I did
my testing on win-xp.

Since I'm a newbie and **really** don't want to spark a python/ruby
talk-back war (I actually like ruby a lot from what I've seen so far), I
was just wondering if there's something I might have missed, like a
psyco equivalent module for ruby or something else to narrow the gap.

I'd appreciate feedback - thanks!
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