while( my $node = $Qjob->dequeue ) {
    if( $node->{canBeSet} ) {
        ## deal with this node
    }
    else {
        $node->{canBeSet} = 1;
        $Q->enqueue( $node ); ## push back for next time.
    }
}

##</code><code>##

sub killThread{
    my $self = shift;
    { lock $self->{threadDone}; $self->{threadDone} = 1; }
    return $self->{thread};
}

sub manageQueue{
    my $self = shift;
    while(1){
        my $done;
        { lock $self->{threadDone}; $done = $self->{threadDone}; }
        my $amtInQ = $queue->pending();
        last if $done && $amtInQ == 0;
        ...

##</code><code>##

sub killThread{
    $queue->enqueue( undef );
}

##</code><code>##

while( 1 ) {
    my $node = $queue->dequeue; 
    if( !defined $node and $queue->pending ){
        $queue->enqueue( undef );
        next;
    }
    else {
        last;
    }
    if( $node->{canBeSet} ) {
        ## deal with this node
    }
    else {
        $node->{canBeSet} = 1;
        $Q->enqueue( $node ); ## push back for next time.
    }
}