use MCE::Loop chunk_size => 1, max_workers => 4;
use DBI;

sub db_iter {
   my $dbh = DBI->connect("dbi:SQLite:dbname=sample.db", "", "", {
      PrintError => 0, RaiseError => 1, AutoCommit => 1,
      FetchHashKeyName => 'NAME_lc',
   });

   my $sth = $dbh->prepare("select fname, lname from people");
   $sth->execute();

   return sub {
      if (my @row = $sth->fetchrow_array) {
         return @row;
      }
      return;
   }
}

mce_loop {
   my ($mce, $chunk_ref, $chunk_id) = @_;
   my ($fname, $lname) = @{ $chunk_ref };

   MCE->say("Hello, $fname $lname");

} db_iter();