package MyHandler;

use strict;
use warnings 'all';
use Apache2::RequestRec;
use Apache2::RequestUtil;

# Declare it here:
my $persistent_thing;

sub handler : method {
  my ($class, $r) = @_;

  # The first time this is executed in a child process, it will be created.
  # After that, you will just reuse the same one:
  $persistent_thing ||= make_the_thing();
}

1;

##</code><code>##

package MyDBI;

use base 'Ima::DBI::Contextual';

my @dsn = ( 'DBI:mysql:dbname:hostname', 'username', 'password', {
  # Other options go here:
  RaiseError => 1,
});
__PACKAGE__->set_db('Main', @dsn);

1;

##</code><code>##

use MyDBI;

# Automatically pooled and recreated if the old one times out or dies:
my $dbh = MyDBI->db_Main;