eval {
    $dbh->do(...);
};
if (my $e = $@) {
    if ($dbh->{Active} != 1 || $dbh->state =~ /08\d{3}/){
        # reconnect and retry
    } else {
        # not connection related error
    }
}

##</code><code>##

unless (fork()) {
    $dbh->{InactiveDestroy} = 0;
    exit;
}
wait();

##</code><code>##

sub query {
    $dbh->selectrow_array(q{ SELECT now() });
}

sub ping_and_query {
    $dbh->selectrow_array(q{ SELECT now() }) if $dbh->ping;
}

cmpthese(-2, {
    'query'      => \&query,
    'ping+query' => \&ping_and_query,
});

---
              Rate ping+query      query
ping+query  6349/s         --       -39%
query      10327/s        63%         --