:)
the module seems vague on claims and evidence, but ,
I just did some testing, and I get these numbers just loading a 51mb file I create
You'll need memusage-workingset-virtualmemory.pl to run it yourself
#!/usr/bin/perl --
use strict;
use warnings;
use Path::Tiny qw/ path /;
use File::Map qw' map_file advise ';
eval { do 'memusage-workingset-virtualmemory.pl'; 1 } or warn $@;
sub memusage() { print mems($$), "\n"; }
my $filename = 'goner-is-gone.txt';
my $fh = path($filename)->openw_raw;
print $fh "01234567789abcdefghijklmnopqrstuvwxyz\n" for 1 .. 1_400_000
+;
close $fh;
print -s $filename, "\n";
memusage();
{
map_file my $map, $filename, '+<';
memusage();
#~ advise( $map, 'sequential' ); ## no visible difference in pslis
+t from normal
#~ advise( $map, 'random' ); ## same
memusage();
my @intervals =
map { $_ * ( 1024 * 1024 ) } 1 .. 100; ## after every mb print
+ something
my $lpos = 0;
while ( $map =~ m{z}g ) {
my $pos = pos($map);
$lpos = $pos;
next if $pos < $intervals[0];
shift @intervals;
print 'pos ', $pos, "\n";
memusage();
}
print "last pos $lpos\n";
memusage();
#~ <>;
}
memusage();
path($filename)->remove;
__END__
53200000
WVM: 21952 { WS: 6164 VM: 3344 }
WVM: 73908 { WS: 6200 VM: 3444 }
WVM: 73908 { WS: 6200 VM: 3444 }
pos 1048609
WVM: 73908 { WS: 7236 VM: 3456 }
pos 2097181
WVM: 73908 { WS: 8264 VM: 3456 }
pos 3145753
WVM: 73908 { WS: 9292 VM: 3456 }
pos 4194325
WVM: 73908 { WS: 10320 VM: 3456 }
pos 5242897
WVM: 73908 { WS: 11344 VM: 3456 }
pos 6291469
WVM: 73908 { WS: 12372 VM: 3456 }
pos 7340041
WVM: 73908 { WS: 13400 VM: 3456 }
pos 8388613
WVM: 73908 { WS: 14428 VM: 3456 }
pos 9437185
WVM: 73908 { WS: 15452 VM: 3456 }
pos 10485795
WVM: 73908 { WS: 16480 VM: 3456 }
pos 11534367
WVM: 73908 { WS: 17508 VM: 3456 }
pos 12582939
WVM: 73908 { WS: 18536 VM: 3456 }
pos 13631511
WVM: 73908 { WS: 19560 VM: 3456 }
pos 14680083
WVM: 73908 { WS: 20588 VM: 3456 }
pos 15728655
WVM: 73908 { WS: 21616 VM: 3456 }
pos 16777227
WVM: 73908 { WS: 22644 VM: 3456 }
pos 17825799
WVM: 73908 { WS: 23668 VM: 3456 }
pos 18874371
WVM: 73908 { WS: 24696 VM: 3456 }
pos 19922981
WVM: 73908 { WS: 25724 VM: 3456 }
pos 20971553
WVM: 73908 { WS: 26752 VM: 3456 }
pos 22020125
WVM: 73908 { WS: 27776 VM: 3456 }
pos 23068697
WVM: 73908 { WS: 28804 VM: 3456 }
pos 24117269
WVM: 73908 { WS: 29832 VM: 3456 }
pos 25165841
WVM: 73908 { WS: 30860 VM: 3456 }
pos 26214413
WVM: 73908 { WS: 31884 VM: 3456 }
pos 27262985
WVM: 73908 { WS: 32912 VM: 3456 }
pos 28311557
WVM: 73908 { WS: 33940 VM: 3456 }
pos 29360129
WVM: 73908 { WS: 34968 VM: 3456 }
pos 30408739
WVM: 73908 { WS: 35992 VM: 3456 }
pos 31457311
WVM: 73908 { WS: 37020 VM: 3456 }
pos 32505883
WVM: 73908 { WS: 38048 VM: 3456 }
pos 33554455
WVM: 73908 { WS: 39076 VM: 3456 }
pos 34603027
WVM: 73908 { WS: 40100 VM: 3456 }
pos 35651599
WVM: 73908 { WS: 41128 VM: 3456 }
pos 36700171
WVM: 73908 { WS: 42156 VM: 3456 }
pos 37748743
WVM: 73908 { WS: 43184 VM: 3456 }
pos 38797315
WVM: 73908 { WS: 44208 VM: 3456 }
pos 39845925
WVM: 73908 { WS: 45236 VM: 3456 }
pos 40894497
WVM: 73908 { WS: 46268 VM: 3456 }
pos 41943069
WVM: 73908 { WS: 47296 VM: 3456 }
pos 42991641
WVM: 73908 { WS: 48320 VM: 3456 }
pos 44040213
WVM: 73908 { WS: 49348 VM: 3456 }
pos 45088785
WVM: 73908 { WS: 50376 VM: 3456 }
pos 46137357
WVM: 73908 { WS: 51404 VM: 3456 }
pos 47185929
WVM: 73908 { WS: 52428 VM: 3456 }
pos 48234501
WVM: 73908 { WS: 53456 VM: 3456 }
pos 49283073
WVM: 73908 { WS: 54484 VM: 3456 }
pos 50331683
WVM: 73908 { WS: 55512 VM: 3456 }
pos 51380255
WVM: 73908 { WS: 56536 VM: 3456 }
pos 52428827
WVM: 73908 { WS: 57564 VM: 3456 }
last pos 53199999
WVM: 73908 { WS: 58320 VM: 3456 }
WVM: 21952 { WS: 6264 VM: 3356 }
So, when you map, seems to signal to the OS this is how big the memory usage is going to go (WVM field), and then the working set slowly increases up to the size of the file as the regular expression advances through the whole file "line" by line
Is this faster than something else? More memory efficien? I dunno
I'm beginning to suspect this is how File::Map is supposed to work
