code: public void startThreads() {
  		if (this.sortThread != null) {
  			this.sortThread.start();
  		}
  		if (this.spillThread != null) {
  			this.spillThread.start();
  		}
  		if (this.mergeThread != null) {
  			this.mergeThread.start();
  		}
  	}
docs: Starts all the threads that are used by this sorter.