Sequence Algorithm Parallelization

People hej,

I am working on porting a Text mining / Natural language application from a single-core Map-Reduce style system. One of the steps involves a while loop like this:

Queue<Element>;

while (!queue.empty()) {
    Element e = queue.next();
    Set<Element> result = calculateResultSet(e);

    if (!result.empty()) {
        queue.addAll(result);
    }
}

Each iteration depends on the result up to (view). It is not possible to determine the number of iterations this loop should perform.

Is there a way to parallelize a sequential algorithm like this one? I'm trying to come up with a feedback mechanism that can provide my own input, but how would I parallelize it?

Thanks for any help / comments