sub doit {
    ....
}

doit( $args[ $_ ] ) for 0 .. $n-1;

##</code><code>##

use threads;

sub doit {
    ...
}

my @threads = map{ 
    threads->new( \&doit, $args[ $_ ] ) 
} 0 .. $n - 1;

$_->join for @threads;