my $threadpool = Thread::Pool->new({
   'do' => \&my_function,
   'optimize' => 'cpu',
 , 'workers'  => 20,
});
$threadpool->job($_) for (@myfiles);
$threadpool->shutdown();

sub my_function {
   my ($file) = @_;
   ...
   return 1;
}

##</code><code>##

Scalars leaked: 1
Scalars leaked: 1
Scalars leaked: -1
Scalars leaked: 1