Re^2: Why does global match run faster than none global?

Cause you're using an old(ish) version of Perl?

       Rate    b    a    c    d
b 3778652/s   --  -1% -19% -21%
a 3817631/s   1%   -- -18% -20%
c 4677165/s  24%  23%   --  -2%
d 4766254/s  26%  25%   2%   --
[download]

This is perl 5, version 14, subversion 0 (v5.14.0) built for i686-linux-thread-multi

Comment on Re^2: Why does global match run faster than none global? Download Code

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Re^3: Why does global match run faster than none global? by BrowserUk (Patriarch) on Aug 23, 2011 at 20:56 UTC
Even more intriguing. The slowest has hardly changed, but the previously faster ones have slowed markedly. `C:\test\perl-5.14.0-RC1>perl use Benchmark qw[ cmpthese ];; print $];; $str = '123456789'; cmpthese -1, { a=>q[ my ($a,$b) = $str =~ m/(23)[^8]+(8)/g; ], b=>q[ my ($a,$b) = $str =~ m/(23)[^8]+(8)/; ], c=>q[ my ($a) = $str =~ m/(23)/g ], d=>q[ my ($a) = $str =~ m/(23)/; ], };; ^Z 5.014000 Rate b a d c b 363518/s -- -17% -35% -46% a 435446/s 20% -- -22% -35% d 555991/s 53% 28% -- -17% c 668598/s 84% 54% 20% --` [download] But still, 20% is not to be sneezed at. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re^3: Why does global match run faster than none global? by Kc12349 (Monk) on Aug 23, 2011 at 20:33 UTC
I'm running strawberry v5.12.3 built for MSWin32-x86-multi-thread. What confuses me, is that by its nature /g seems like it should run longer.	[reply]
Re^4: Why does global match run faster than none global? by ikegami (Patriarch) on Aug 23, 2011 at 20:52 UTC
Why would it take longer? All the /g version does in addition to the non-/g version is check if "9" is "23". Actually, it doesn't even get that far. It knows a minimum of 4 chars is needed for another match, yet there's only one char left.	[reply]
Re^5: Why does global match run faster than none global? by Kc12349 (Monk) on Aug 23, 2011 at 21:08 UTC
Fair enough, but in the case of searching for m/(23)/, /g will continue to the end of the string, while none /g should stop after its match. In this case it still seems like /g should be slower, though surely I could confused or missing something.	[reply]
Re^6: Why does global match run faster than none global? by ikegami (Patriarch) on Aug 23, 2011 at 22:37 UTC
Re^3: Why does global match run faster than none global? by BrowserUk (Patriarch) on Aug 25, 2011 at 04:12 UTC
You did ensure that `$str` was defined as our not my didn't you?	[reply] [d/l]