public void stopFilling() {
		checkNotNull(bucketFillerExecutor, "Bucket filler is not running.");
		bucketFillerExecutor.shutdownNow();
		try {
			bucketFillerExecutor.awaitTermination(10, SECONDS);
		} catch (InterruptedException e) {
			log.error("Timed out waiting for bucket filler thread to shut down: ", e);
		} finally {
			bucketFillerExecutor = null;
			filling = false;
		}
	}