my $max_retry =3;
RETRY: while (my $n_attempt=0, $parameter=<>)
{
   my $req = POST 'http:/...blah..../',
                   [ 
                     action   => '/db/',
                     param    => "$parameter",
                     type     => 'submit', 
                     value    => 'Search',
                   ];

   my $res = $ua->request($req);
   
   # idea is to concentrate the "it didn't work" code to
   # right here
   unless ($res->is_success) ##1 of 5,000 case##
   {
      $n_attempt++;
      print STDERR "attempt # $n_attempt for $parameter\n";
      print STDERR "$parameter ERROR: Try# $n_attempt of $max_retry: ".
                   $res->status_line . "\n";
      sleep(1);
      redo RETRY if $n_attempt <= $max_retry;
      print STDERR "$parameter ERROR: Try# $n_attempt of ".
                    "$max_retry FAILED: ".
                    $res->status_line . "\n";                 
      next; #we "Give up" at this point! And read next 
            #parameter from <>
   }
   
### this is the "good machine case..."
   print $res->as_string if DEBUG_RAW;
   ......or whatever....
}