On Thu, 8 Sep 2005, Nigel Metheringham wrote:
> However perl is normally pretty fast for regexp application (especially
> as you do need to do all that horrid UTF8 stuff) although there are
> cases that go really nasty.
Well, all I can say is that when I feed the PCRE pattern matching tests
to Perl, they run much more slowly. This is the main test, which has 704
different patterns, with various numbers of data lines:
Using pcretest:
real 0m0.003s
user 0m0.000s
sys 0m0.001s
Using Perl:
real 0m1.000s
user 0m0.974s
sys 0m0.007s
However, I haven't taken any measures to optimize the Perl (for example,
it probably recompiles each pattern for each match). Therefore, these
are "worst case" figures which no doubt could be improved. Nevertheless,
I would not expect Perl ever to be able to catch up: it is, after all,
essentially an interpreted language. You cannot expect it to be as fast
as compiled code. Even a few percent can be important when millions of
regex matches are happening.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book: http://www.uit.co.uk/exim-book
