code: float refreshAndGetAvg() {
  		long total = 0;
  
  		ResultSubpartition[] allPartitions = partition.getAllPartitions();
  		for (ResultSubpartition part : allPartitions) {
  			int size = part.unsynchronizedGetNumberOfQueuedBuffers();
  			total += size;
  		}
  
  		return total / (float) allPartitions.length;
  	}
docs: Iterates over all sub-partitions and collects the average number of queued buffers in a
  sub-partition in a best-effort way.
  
  @return average number of queued buffers per sub-partition