$ perl -le "use Readonly; Readonly::Scalar $LU => 66; use threads; async{ print join q/ /, threads->tid, $LU, \$LU } for 1..3; sleep 1; "
1 66 SCALAR(0xb84cfc)
2 66 SCALAR(0xc1bbec)
3 66 SCALAR(0x10af0b4)
Perl exited with active threads:
        0 running and unjoined
        3 finished and unjoined
        0 running and detached