Hello BrowserUk,
I running on: This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-linux-gnu-thread-multi and I can see two different observations based on your script.
When I am executing your script with new line characters \n sample of the script bellow:
#!/usr/bin/perl
use strict;
use warnings;
use Benchmark ':hireswallclock'; # enable hires wallclock (microsecond
+s) timing if possible
my $iterations = 1;
my $regexEngineCode = sub {
my $x = "the quick brown fox\n"; $x x= 107374182; print length $x
+. "\n"; ### 8 bytes less than 2^31.
my $n=0; ++$n while $x =~ m[^.*$]mg; print $n . "\n"; ### finds al
+l the lines.
### Add another line that pushes the length a few bytes over 2^
$x .= "the straw that broke the camel's back\n"; print length $x .
+ "\n";
$n=0; ++$n while $x =~ m[^.*$]mg; print $n . "\n"; ### and it sile
+ntly fails to find any of them.
};
my $time = timeit($iterations, $regexEngineCode);
print "It took ", timestr($time), "\n";
I am getting the following output:
2147483641107374182
Out of memory!
real 1m29.931s
user 0m50.376s
sys 0m4.824s
I forgot to mention I am using also Benchmark and time(1) - Linux man page to see the process time.
But when I remove the new line characters \n sample of code bellow:
#!/usr/bin/perl
use strict;
use warnings;
use Benchmark ':hireswallclock'; # enable hires wallclock (microsecond
+s) timing if possible
my $iterations = 1;
my $regexEngineCode = sub {
my $x = "the quick brown fox\n"; $x x= 107374182; print length $x;
+ ### 8 bytes less than 2^31.
my $n=0; ++$n while $x =~ m[^.*$]mg; print $n; ### finds all the l
+ines.
### Add another line that pushes the length a few bytes over 2^
$x .= "the straw that broke the camel's back\n"; print length $x;
$n=0; ++$n while $x =~ m[^.*$]mg; print $n . "\n"; ### and it sile
+ntly fails to find any of them.
};
my $time = timeit($iterations, $regexEngineCode);
print "It took ", timestr($time), "\n";
I get on the output:
214748364010737418221474836780
It took 32.7849 wallclock secs (31.79 usr + 1.02 sys = 32.81 CPU) @
+0.03/s (n=1)
real 0m32.942s
user 0m31.839s
sys 0m1.129s
So based on the observations/results provided by karlgoethebier above, shows that if you have appropriate HW, you can get a complete output on v5.18.2 even if with the new line characters. Instead of my HW failure. Although that on the 4th print statement he is getting a zero indicating that probably Perl v5.18.2 can not handle so big numbers.
So in conclusion I would say a combination of HW and latest SW version of Perl can provide you with the result that you expect.
Update: I am not expert (not even close) but I think this might be the reason. Short description about memory limitation between LinuxOS and WindowsOS Memory Limits in R.
Update 2: I also found this regarding Perl 5.20.0 Better 64-bit support:
On 64-bit platforms, the internal array functions now use 64-bit offsets, allowing Perl arrays to hold more than 2**31 elements, if you have the memory available.
The regular expression engine now supports strings longer than 2**31 characters. perl #112790, #116907
The functions PerlIO_get_bufsiz, PerlIO_get_cnt, PerlIO_set_cnt and PerlIO_set_ptrcnt now have SSize_t, rather than int, return values and parameters..
Update 3: update hyper-link and modified text output.
Hope this helps.
Seeking for Perl wisdom...on the process of learning...not there...yet!
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