title: Waiting for ParallelFlux completion
body: <p>I have created a <code>ParallelFlux</code> and then used <code>.sequential()</code>, expecting at that point I can count or "reduce" the results of the parallel computations. The problem seems to be that the parallel threads are fired off and nothing is waiting for them. </p>
  
  <p>I have sort of gotten things to work using a <code>CountDownLatch</code> but I don't think I should have to do that.</p>
  
  <p>TL;DR - I cannot get a result to print out for this code:</p>
  
  <pre><code>    Flux.range(0, 1000000)
      .parallel()
      .runOn(Schedulers.elastic())
      .sequential()
      .count()
      .subscribe(System.out::println);
  </code></pre>