It's easily possible to keep objects persistent per Apache process using mod_perl. If you need finer grained resolution, like for example per-user or per-session, then looking into one of the Session modules is worth it. Not every session module can handle large objects, as not all of them employ Storable to persist your large objects.

I tried to use CGI::Session together with CGI for keeping CustomObject between web page updates:

/cgi-bin/session:

#!/usr/bin/perl -wT
use strict;
use warnings;
use CGI;
use CGI::Session;
use CustomObject;

my $cgi = new CGI;
my $session = new CGI::Session("driver:File", $cgi, {Directory => "/tm
+p"});
print $cgi->header(-type    => "text/html",
                   -charset => "utf-8"),
      $cgi->start_html("Session management");
# Initialize session object.
unless ($session->param("custom_object")) {
    my $customObject = new CustomObject("test_login", "test_password")
+;
    $session->param("custom_object", $customObject);
    print $cgi->p("Custom object initialized");
}
my $customObject = $session->param("custom_object");
print $cgi->p("Login: " . $customObject->login()),
      $cgi->p("Password: " . $customObject->password()),
      $cgi->end_html();
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/usr/lib/perl5/site_perl/CustomObject.pm:

package CustomObject;

sub login {
    my $self = shift;
    return $self->{LOGIN};
}

sub new {
    my ($className, $login, $password) = @_;
    my $self = bless {
        LOGIN => $login,
        PASSWORD => $password
    }, $className;
    return $self;
}

sub password {
    my $self = shift;
    return $self->{PASSWORD};
}

1;
[download]

All I get is that CustomObject is instantiated each web page update and the /tmp directory is populated with cgisess_* files.

It's easily possible to keep objects persistent per Apache process using mod_perl.

Bad idea. It's very unlikely you'll get the same Apache process on the next request.