unique cookie id?

rkg has asked for the wisdom of the Perl Monks concerning the following question:

Hi -- Can I be assured the following code generates a unique cookie id in a mod_perl environment?

ToBase62 just converts an int to base62 representation(A-Z,a-z,0-9).

Do I need to worry about different length pids?

Thanks

sub generate_id {
    my $id = $ToBase62->(time) . $ToBase62->($$) . ToBase62->( rand($$
+) );
    return $id;
}
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