@Override
  public void close() {
    try {
      flushWrites();
      itemQueue.put(doneSentinel);
    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      throwFatalException(e);
    } catch (Exception e) {
      throwFatalException(e);
    }
  }
Creates a new {@code WeightedHandoffQueue} with {@code outer} maximum number of pending batches and {@code inner}
maximum batch weight.
planetiler-core/src/main/java/com/onthegomap/planetiler/worker/WeightedHandoffQueue.java