use MCE::Simple -strict, max_workers => 16;

use MCE::Semaphore;
use Time::HiRes 'time';

my $start = time;
my $sem = MCE::Semaphore->new(8);

mce_foreach_s ( 1 .. 1_000_000 ) {
    $sem->down;
    $sem->up;
}

printf "%0.3f seconds\n", time - $start;