What's the best way of executing tasks in parallel in Ksh and Perl?

my @make_obj = qw(
  obj1.o
  obj2.o
  obj3.o
  ...
);

my $fm = $pm = new Parallel::ForkManager(6);
foreach my $obj (@make_obj) {
  $fm->start and next;
  system("make -f Makefile $make_obj");
  $fm->finish();
}

use threads;

my $max_threads = 5;

my @targets = qw(obj1.o obj2.o obj3.o ...);
while(@targets) {
    my $num_threads = threads->list(threads::running);
    if( $num_threads < $max_threads ) {
        my $target = shift @targets;
        threads->create(sub { return system "make $target" });
    }
}

make -f Makefile obj1.o &
make -f Makefile obj2.o &
...
make -f Makefile objn.o &