From: "David G. Andersen" <dga@...>
Date: 2004-10-20T04:58:02+09:00
Subject: Speed gap between zcat and zlib's GzipReader

I'm still in 1.8.1-land, so this may be old news, but 
GzipReader is (painfully) slow compared to using zcat
to accomplish the same thing:

The code:

#!/scratch/ruby/bin/ruby

require 'zlib'

f = ARGV[0]

s = Time.new
infile = Zlib::GzipReader.new(File.new(f, "r"))
#infile = IO.popen("zcat #{f}", "r")
linecount = 0
infile.each_line { |l|
  linecount += 1
}
e = Time.new
print "Read #{linecount} lines in #{e - s} seconds\n"

------------------------------

Tested on:
FreeBSD port-installed ruby 1.8.1
Freshly compiled 1.8.1
Freshly compiled 1.8.1 with CFLAGS=-O2
CVS version, CFLAGS=-O2

            FBSD 1.8.1   1.8.1, O0  1.8.1 -O2  CVS, -O2
popen zcat:      2.3      2.3       2.3        2.3
GzipReader:      5.8      9.2       5.8        5.9

Yowza.  Before I poke more, is this expected, or a known
slowness issue?

  -Dave

-- 
work: dga@lcs.mit.edu                          me:  dga@pobox.com
      MIT Laboratory for Computer Science           http://www.angio.net/