my $bits :shared = chr(0); $bits x= $N/ 8 + 1;
my $t = async{
    while( defined( $_ = $Qn_1->dq ) ) {
        die "value duplicated" if vec( $bits, $_, 1 );
        vec( $bits, $_, 1 ) = 1;
    }
};

##</code><code>##

D'ok 1 - got 1 from queue
D'ok 2 - got 2 from queue
D'ok 3 - got 3 from queue
D'ok 4 - got 4 from queue
D'ok 5 - got 5 from queue
D'ok 6 - got 6 from queue
D'ok 7 - got 7 from queue
D'ok 8 - got 8 from queue
D'ok 9 - got 9 from queue
...
D'ok 99996 - got 99996 from queue
D'ok 99997 - got 99997 from queue
D'ok 99998 - got 99998 from queue
D'ok 99999 - got 99999 from queue
D'ok 100000 - got 100000 from queue