use strict;
use warnings;

use threads qw(yield);
use threads::shared;
use Data::Dumper;

sub test { 
    my %h : shared; 
    for (1..3) { 
        threads->new(sub { 
            my($n) = @_;
            lock(%h); 
            $h{$n} = rand(); 
            threads->yield(); 
        }, $_)->join();
    } 
    return %h;
} 

my %k = test(); 
print Dumper(\%k);