You would fork inside your

foreach $task (@tasks) {
    $task->do_one_task()
};
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It might go like this (see fork for more error checking):

foreach $task (@tasks) {
    use POSIX ':sys_wait_h';
    my $child = fork();
    if ($child) {
        for (my $polls = 30; waitpid($child, WNOHANG) == 0; --$polls) 
+{
            if ($polls < 1) {
                print "Game over...killing $child\n";
                kill 'ABRT', $child;
                # Maybe return some code, or exit here
            }
            sleep 1;
        }
    }
    else {
        $task->do_one_task()
        exit 0;
    }
}
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or, probably better:

    my $child = fork();
    if ($child) {
    $SIG{ALRM} = sub {
        print "Game over...killing $child\n";
        kill 'ABRT', $child;
        # Maybe return some code, or exit here
    };
    alarm 10;
    # Waiting for child or alarm
    waitpid($child, 0);
    }
    else {
        $task->do_one_task()
        exit 0;
    }
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