sub mod_perl_wrapper {
   ##### Begining of script #####
   use strict;
   use warnings;

   my $global = $_[0];   # Say some value from the request.

   sub foo {
      # Warms 'Variable "$global" will not stay shared'
      print("$global\n");
   } 

   foo();

   ##### End of script #####
}

mod_perl_wrapper(4);  # First request prints "4"
mod_perl_wrapper(5);  # Subsequent requests also prints "4"