for(my $i=0; $i< @hosts; $i++){
    $pm->start($hosts[$i]) and next;   
    system(@some_command);
    $return_code = $? >> 8;
    $pm->finish($return_code);
}

##</code><code>##

use POSIX qw( _exit );

for(my $i=0; $i< @hosts; $i++){
    $pm->start($hosts[$i]) and next;   
    system(@some_command);
    $return_code = $? >> 8;
    _exit($return_code);
}

##</code><code>##

for my $host (@hosts) {
    $pm->start($host) and next;   
    exec(@some_command);
}

##</code><code>##

for my $host (@hosts) {
    $pm->start($host) and next;   
    exec(@some_command);
    print(STDERR "exec failed: $!\n");
    _exit($!);
}