#! perl -slw
use strict;
use threads;
use threads::shared;

our $X :shared; $X ||= 10;
our $Y :shared; $Y ||= 10;

sub background {
    my $AoA = shift;
    while( 1 ) {
        $AoA->[ rand $Y ][ rand $X ]++;
        select undef, undef, undef, 0.01;
    }
}

my $AoA: shared = &share( [] );
@{ $AoA } = map{ &share( [] ) } 1 .. $Y;

@{ $AoA->[ $_ ] } = (0) x $X for 0 .. $X-1;

async \&background, $AoA;

while( 1 ) {
    system 'cls';
    print "@$_" for @{ $AoA };
    select undef, undef, undef, 0.1;
}