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egrep performance with large standard quantifiers
From: |
Adam Monsen |
Subject: |
egrep performance with large standard quantifiers |
Date: |
Thu, 22 Jun 2006 16:49:43 -0700 |
I'm not sure if this is a bug, but does anyone have a clue why egrep is so
dang slow when using large standard quantifiers?
$ echo "foo" | time egrep -q '^.{1,2000}$'
11.65user 0.10system 0:11.75elapsed 100%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (0major+16326minor)pagefaults 0swaps
For reference, here's Perl:
$ echo "foo" | time perl -ne 'm/^.{1,2000}$/'
0.00user 0.00system 0:00.00elapsed 200%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+420minor)pagefaults 0swaps
Maybe the finger really points at pcre. I don't know.
I'm tried this with a few different versions, but for reference' sake,
here's what I was using:
grep 2.5.1
pcre 4.5
perl 5.8.5
(all from a standard CentOS 4.3 install)
--
Adam Monsen
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