code: protected void initInputsSerializersAndComparators(int numInputs) throws Exception {
  		this.inputSerializers = new TypeSerializerFactory<?>[numInputs];
  		this.inputComparators = this.driver.requiresComparatorOnInput() ? new TypeComparator[numInputs] : null;
  		this.inputIterators = new MutableObjectIterator[numInputs];
  		
  		for (int i = 0; i < numInputs; i++) {
  			//  ---------------- create the serializer first ---------------------
  			final TypeSerializerFactory<?> serializerFactory = this.config.getInputSerializer(i, this.userCodeClassLoader);
  			this.inputSerializers[i] = serializerFactory;
  			
  			//  ---------------- create the driver's comparator ---------------------
  			if (this.inputComparators != null) {
  				final TypeComparatorFactory<?> comparatorFactory = this.config.getDriverComparator(i, this.userCodeClassLoader);
  				this.inputComparators[i] = comparatorFactory.createComparator();
  			}
  
  			this.inputIterators[i] = createInputIterator(this.inputReaders[i], this.inputSerializers[i]);
  		}
  	}
docs: Creates all the serializers and comparators.