FLASH4 complete API

  Returns the global status of the pipeline. This is a blocking operation that
  currently determines, if the pipeline is considered empty, i.e. there are no
  more items in the pipeline.

  Procedure:

  The item balance counts (number of items added vs. number of items removed from
  pipeline) on each processor are all summation reduced and the resulting total
  pipeline item count redistributed on all processors. Since the number of total
  items in the pipeline cannot be < 0, a negative number indicates a bug someplace.
  Note that the individual processor item balance counts can be < 0. This happens
  if on a processor no items were fed into the pipeline, but many items were retrieved
  on that same processor.