use strict; use warnings; use feature 'say';
use Parallel::ForkManager;
use Time::HiRes qw/ time /;

$|++;

my $forker = Parallel::ForkManager->new(4);
say "v.1";
for ( 0 .. 9 ) {
    my $pid = $forker->start;
    if ( $pid ) {
        say "1 $$ $_ start: " . time;
        sleep 1;
    }
    $forker->finish;
}

my $forker2 = Parallel::ForkManager->new(4);
say "v.2";
for ( 0 .. 9 ) {
    my $pid = $forker->start and next;
    say "2 $$ $_ start: " . time;
    sleep 1;
    $forker->finish;
}

__END__