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.

Let me ask you a simple question, how is your session ID being stored on the web page?

I don't see your session ID being stored as a cookie, nor as a hidden variable anywhere. How is the web page supposed to know which session you are referring too?

Figure out how to manage your session ID on the web page and then use that ID to retrieve a specific session. Then you will be alright.

Are you sure that your session works without your object?

I use the object instantiation exactly to find out if the session is kept between page updates which I can't see. What should I do?

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