...
    unless ($client = $lsn->accept) {
        tprint ("Could not connect to socket: " . $!);
        next;
    }
    if( threads::list( threads::running >= 100 ) {
        $client->shutdown( 2 );
        $client->close;
        tprint( "Client $client rejected; too many concurrent clients." );
        next;
    }
    ...