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Re: [perl #121230] process group kill on Win32 broken in 5.17.2,regression 5.18

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From:
Dave Mitchell
Date:
April 24, 2014 14:54
Subject:
Re: [perl #121230] process group kill on Win32 broken in 5.17.2,regression 5.18
Message ID:
20140424145411.GA3895@iabyn.com
On Wed, Apr 23, 2014 at 01:34:21PM +0200, demerphq wrote:
> On 18 March 2014 13:46, H.Merijn Brand <h.m.brand@xs4all.nl> wrote:
> > On Tue, 18 Mar 2014 13:15:11 +0100, demerphq <demerphq@gmail.com> wrote:
> >
> >> > The difference in parsing time between single and double quotes strings is
> >> > infinitesimal
> >>
> >> IMO there is no point in worrying about these kind of things unless
> >> the string is very long.
> >
> > And not even then. I benched it years ago on several machines, and all
> > bench results are in line-noise margins and differ per architecture.
> > IIRC all big-endian boxes I tried on had a <1% preference for double
> > quotes whereas little-endian boxes prefered single quotes.
> 
> Well no, when the string becomes long it starts being interesting to
> not use a quoted string, or to use single quoted here docs.
> 
> When I checked last Perl has non-linear and degrading performance
> parsing strings. The longer the string the slower it gets.
> 
> In practice unless the string is quite long (hundreds to thousands of
> characters) it is not something you need to worry about at all. On the
> other hand if you happen to be dealing with a case where you are
> generating code with lots of long quoted strings you can see real
> parsing performance gains by removing the strings.

The double-quoted parsing code is very inefficient. It does a lot of
checks for each char position in the string; I suspect we could speed it
up tremendously by doing a strchr() or similar to skip to the next
"interesting" char, and only then doing all the checks.

-- 
It's not that I'm afraid to die, I just don't want to be there when it
happens.
    -- Woody Allen

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