use Module::Load::Conditional qw[can_load];
# Are we running threads?
my $grThreaded = eval 'use threads; 1';
# If so, load thread modules
my ($grThreadModules) = {
    'threads::shared'   =>  undef,
    'Thread::Semaphore' =>  undef,
    };
if ( $grThreaded )
{
    unless ( can_load( modules => $grThreadModules ) )
    {
        print "ERROR: Cannot load threaded modules in $0. Exiting.";
        exit();
    }
}
use strict;

my($gnWarning);

if ( $grThreaded )
{
    # Does not work at all: Undefined subroutine &main::share
#    share($gnWarning);
    # This works in the debugger
    # However, if used in production:  
    #  Argument to share needs to be passed as ref
#    threads::shared::share($gnWarning);
    # This works at run time
    # However, if used under the debugger:
    # Type of arg 1 to threads::shared::share must be one of [$@%]
    #   (not single ref constructor)
    threads::shared::share(\$gnWarning);
}