coro.pl

use strict;
use warnings;
use Coro ();
use Benchmark ':all';
use DateTime;

cmpthese(
    10000 => {
        'fork' => sub {
            my $pid = fork();
            if ($pid == 0) { # child
                exit;
            } elsif ($pid) { # parent
                waitpid($pid, 0);
            } else {
                die $!;
            }
        },
        coro => sub {
            my $coro = Coro::async(sub { });
            $coro->join;
        },
    },
);

ithreads.pl

use strict;
use warnings;
use threads;
use Benchmark ':all';
use DateTime;

cmpthese(
    1000 => {
        threads => sub {
            threads->create(sub { })->join;
        },
        'fork' => sub {
            my $pid = fork();
            if ($pid == 0) { # child
                exit;
            } elsif ($pid) { # parent
                waitpid($pid, 0);
            } else {
                die $!;
            }
        },
    },
);