Re^2: Inexplicably slow regex

Even with 0.5MB: Still can't confirm!

use Benchmark qw( cmpthese );
our $KEY="df";

{
    local $/;
    open my $hosts,'/etc/hosts';
    $_= <$hosts>;
    close $hosts;
}
$_= $_ x (0.5*1024*1024 / length $_);
s/$KEY/XX/g;
$_.= "\n    df   ";

print length $_,"\n";


cmpthese(-3, {
   caret => '/^ \s* $KEY /mx',
   cr => '/\n \s* $KEY /mx',
});
[download]

Result

524114
Rate cr caret
cr 1108181/s -- -1%
caret 1118184/s 1% --

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

Comment on Re^2: Inexplicably slow regex Select or Download Code

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Re^3: Inexplicably slow regex by Anonymous Monk on Sep 13, 2006 at 00:22 UTC
It looks like it needs many lines to have a partial match in order to slow things down. Try executing this line before adding the matching line: `s/^/ /mg;` [download]	[reply] [d/l]
Re^4: Inexplicably slow regex by Skeeve (Parson) on Sep 13, 2006 at 06:48 UTC
I've put the line just before `$_.= "\n df ";` and still no big difference: `542450` `Rate cr caret` `cr 1105787/s -- -2%` `caret 1131435/s 2% --` `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re^5: Inexplicably slow regex by Anonymous Monk on Sep 13, 2006 at 16:45 UTC
Thanks for your efforts. I'm at a loss to explain the differences you're seeing. I'm obviously using different input data. It would be interesting to know whether your results differ from the example provided by the user grandfather, since he was able to create a complete self-contained example.	[reply]