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This queue is for tickets about the Regexp-MatchContext CPAN distribution.

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The Basics
Id: 41936
Status: new
Priority: 0/
Queue: Regexp-MatchContext

People
Owner: Nobody in particular
Requestors: jpierce [...] cpan.org
Cc:
AdminCc:

Bug Information
Severity: Important
Broken in: 0.0.2
Fixed in: (no value)



Subject: False performance claims in POD
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text/plain 2.4k
"only impacts the performance of matches that you specify." I ran several Benchmarks for comparison, and it seems to still impact performance (this is 5.8.4) on non-match-capturing expressions due to the fact that the overloaded qr still includes a code block (?-xism:(?{$Regexp::MatchContext::target_ref=undef})[^aeiou]{3}) Below is my test code: use Benchmark; # my $RE = qr/(?p)[^aeiou]{3}/; use English; my $RE = qr/[^aeiou]{3}/; #use Regexp::MatchContext -vars; my $RE = qr/(?p)[^aeiou]{3}/; #use Regexp::MatchContext -vars; my $RE = qr/[^aeiou]{3}/; timethis(100_000 => sub{ foreach( qw/hippopotamus Schadenfreude xyzzy supercalifragilisticexpialidocious/ ){ 1 if /$RE/; } } ); __END__ Perl timethis 100000: 2 wallclock secs ( 1.85 usr + 0.00 sys = 1.85 CPU) @ 54083.29/s (n=100000) timethis 200000: 4 wallclock secs ( 3.71 usr + -0.00 sys = 3.70 CPU) @ 53981.11/s (n=200000) E timethis 100000: 3 wallclock secs ( 1.90 usr + 0.00 sys = 1.90 CPU) @ 52742.62/s (n=100000) timethis 200000: 5 wallclock secs ( 3.80 usr + 0.00 sys = 3.80 CPU) @ 52687.04/s (n=200000) RMC w/p timethis 100000: 7 wallclock secs ( 6.92 usr + 0.00 sys = 6.92 CPU) @ 14446.69/s (n=100000) timethis 200000: 14 wallclock secs (13.60 usr + 0.00 sys = 13.60 CPU) @ 14704.80/s (n=200000) RMC no-p timethis 100000: 3 wallclock secs ( 4.06 usr + 0.00 sys = 4.06 CPU) @ 24636.61/s (n=100000) timethis 200000: 8 wallclock secs ( 8.06 usr + 0.00 sys = 8.06 CPU) @ 24823.14/s (n=200000) This patch --- site_perl/5.8.0/Regexp/MatchContext.pm~ Thu Aug 4 01:58:14 2005 +++ site_perl/5.8.0/Regexp/MatchContext.pm Wed Dec 24 15:00:16 2008 @@ -33,8 +33,7 @@ } { push @vars, "undef\$$1;"; "($2)(?{eval'\$$1=\$^N'})" }gex and $raw =~ s/$/|(??{@vars'(?!)'})/; - $raw =~ s/\(\?p\)/(?{\$Regexp::MatchContext::target_ref=\\\$_})/g - or $raw =~ s/\A/(?{\$Regexp::MatchContext::target_ref=undef})/; + $raw =~ s/\(\?p\)/(?{\$Regexp::MatchContext::target_ref=\\\$_})/g; return $raw; }; Gives performance as documented: timethis 100000: 2 wallclock secs ( 1.84 usr + 0.00 sys = 1.84 CPU) @ 54377.38/s (n=100000) timethis 200000: 4 wallclock secs ( 3.69 usr + 0.00 sys = 3.69 CPU) @ 54156.51/s (n=200000)


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