package Iter::Output;

sub new {
   my ( $class, $path ) = @_;
   my ( $order_id, $fh, %hold ) = ( 1 );

   # Note: Do not open the file handle here, during construction.
   # The reason is that sharing will fail (cannot serialize $fh).

   MCE::Shared->share(
      bless [ $path, $fh, \$order_id, \%hold ], $class
   );
}

sub send {
   ...
}

sub close {
   ...
}