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Perl: the Markov chain saw

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Seemed odd to me, so I ran it on 5.8.8 and the current bleadperl 5.11. The absolute numbers for my computer are, of course, different, but the general observation holds for 5.11. The really disturbing part is that 5.8.8 executes the atomic1/2 cases at about the same speed as "normal". Oh, and on a side note: The difference in execution speed of 5.11's "normal" and 5.8.8's "normal" may be due to 5.11 being a debugging build and all, so it's not necessarily significant.

#!/usr/bin/perl use strict; use warnings; use version; use Benchmark qw(cmpthese); my $str = "bea" x 100; my $re = qr/(?:be|ea|a)/; cmpthese(-2, { atomic1 => sub { die if $str =~ m/(?>$re+)\d/ }, atomic2 => sub { die if $str =~ m/(?>$re)+\d/ }, normal => sub { die if $str =~ m/$re+\d/ }, ( version->new($]) >= version->new("5.10.0") ? (posessive => sub { die if $str =~ m/$re++\d/ }) : () ), }); __END__ 5.8.8: Rate normal atomic2 atomic1 normal 5000/s -- -4% -18% atomic2 5208/s 4% -- -15% atomic1 6132/s 23% 18% -- 5.11: Rate posessive atomic1 atomic2 normal posessive 59.9/s -- -1% -97% -97% atomic1 60.4/s 1% -- -97% -97% atomic2 1953/s 3159% 3134% -- -9% normal 2156/s 3500% 3472% 10% --

I'm hoping for demerphq to chime in with an explanation. :)


In reply to Re: Performance of possessive quantifiers by tsee
in thread Performance of possessive quantifiers by moritz

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