sub task {
    my ($id, $val) = @_;
    say "Hobo $id started";
    for ( 1 .. 100000 ) {
       $mutex->lock;
       $val = $number->incr();
       $mutex->unlock;
    }
    say "Hobo $id ended";
}

__END__

Hobo 1 started
Hobo 2 started
Hobo 3 started
Hobo 4 started
Hobo 3 ended
Hobo 4 ended
Hobo 1 ended
Hobo 2 ended
duration: 9.702 seconds
number: 400000