code: private void closeInputGates() throws IOException, InterruptedException {
  		for (int i = 0; i < this.inputGates.size(); i++) {
  			final InputGate<? extends IOReadableWritable> eig = this.inputGates.get(i);
  			// Important: close must be called on each input gate exactly once
  			eig.close();
  		}
  
  	}
docs: Closes all input gates which are not already closed.