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Strange performance bug
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Date: 2009-04-29 (03:37)
From: Markus Mottl <markus.mottl@g...>
Subject: Re: [Caml-list] Strange performance bug
On Tue, Apr 28, 2009 at 22:43, Brighten Godfrey <pbg@cs.berkeley.edu> wrote:
> I've encountered a very odd performance problem which I suspect is not a bug
> in my code.  Could it be the compiler, or maybe PCRE?

I'm not sure it solves your problem (haven't tried the example), but
just looking at the code there is clearly a performance bug: the
pattern is passed to Pcre.pmatch "on the fly" using label "~pat".
This is ok and convenient if it is used only once, but is bad if it
happens in a loop.  Precompile the regular expression outside of the
loop (let rex = Pcre.regexp "...") and pass it in with label "~rex" to
solve this problem.


Markus Mottl        http://www.ocaml.info        markus.mottl@gmail.com