List Generation
Use map instead of for when generating new lists from old.
####
use strict;
use warnings;
use Benchmark qw(:all);
my @results;
my $count = -5;
# Populate list with 10 mio numbers
for (my $i=0; $i<1000_000; $i++) {
push @results, $i;
}
cmpthese (
$count,
{
for => "test_for;",
map => "test_map;",
}
);
timethese($count, {
for => "test_for;",
map => "test_map;",
}
);
sub test_for {
my @sqrt_results;
for my $result (@results) {
push @sqrt_results , sqrt($result);
}
}
sub test_map {
my @sqrt_results = map { sqrt $_ } @results;
}
##
##
$count=-1
(warning: too few iterations for a reliable count)
Rate for map
for 2.67/s -- -10%
map 2.98/s 12% --
$count=-5
Rate map for
map 3.05/s -- -16%
for 3.61/s 18% --
$count=-10
Rate for map
for 2.73/s -- -8%
map 2.95/s 8% --
##
##
$count=-1
Benchmark: running for, map for at least 1 CPU seconds...
for: 1 wallclock secs ( 1.16 usr + 0.00 sys = 1.16 CPU) @ 3.46/s (n=4)
map: 2 wallclock secs ( 1.19 usr + 0.00 sys = 1.19 CPU) @ 3.37/s (n=4)
$count=-5
Benchmark: running for, map for at least 5 CPU seconds...
for: 6 wallclock secs ( 5.22 usr + 0.00 sys = 5.22 CPU) @ 3.64/s (n=19)
map: 6 wallclock secs ( 5.22 usr + 0.00 sys = 5.22 CPU) @ 3.45/s (n=18)
$count=-10
Benchmark: running for, map for at least 10 CPU seconds...
for: 10 wallclock secs (10.11 usr + 0.00 sys = 10.11 CPU) @ 3.46/s (n=35)
map: 10 wallclock secs (10.03 usr + 0.00 sys = 10.03 CPU) @ 3.29/s (n=33)