async {
    while( $Q->dequeue() ) {
        ## process message.
    }
};

async {
    until( $dieNow  ) {
        sleep $someTime;
        ## do housekeeping.
    }
};

##</code><code>##

while( my( $nfound, $timeleft) = select( ..., $timeout ) ) {
    if( $timeleft ) {
         ## Nothing doing, do some housekeeping
    }
    else {
        ## deal with the event
    }
}

##</code><code>##

use Time::HiRes qw[ sleep ];
...
    until( $dieNow ) {
        sleep( $timeout / 10 );
        if( my $dgram = $Q->dequeue_nb() ) {
             ## Act on $dgram
        }
        else {
             ## Do housekeeping (if required).
        }
    }

##</code><code>##

async{ 1 while Win32::Sleep( 100 ); }->join;;