If you use a package variable, it will be shared by all instances of the class, with or without sharing. Instance variables, even shared instance variables, need to be embedded within the instance.

Try this and see how you get on:

package Counter;

use strict;
use threads;
use threads::shared;

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self = {};

    my $counter :shared = shift; ## Local shared variable

    $self->{ counter } = \$counter; ## Store a reference to it in the 
+object

    bless($self,$class);
    return $self;
}

sub incCounter {
    my $self = shift;
    lock ${ $self->{ counter } };
    ++${ $self->{ counter } };
}

sub getCounter {
    my $self = shift;
    lock ${ $self->{ counter } };
    ${ $self->{ counter } };
}
1
[download]

#! perl -slw
use strict;
use threads;
use Counter;

my $t1 = async{
    my $c1 = Counter->new( 100 );
   $c1->incCounter while $c1->getCounter < 10000;
   return $c1->getCounter;
};

my $t2 = async{
    my $c2 = Counter->new( 100 );
   $c2->incCounter while $c2->getCounter < 30000;
   return $c2->getCounter;
};

print $t1->join;
print $t2->join;

__END__
C:\test>junk54
10000
30000
[download]