public static void main(String args[])
	{
		long begin=System.currentTimeMillis();
		int total=219521;
		int limit=20000;
		ExecutorService executorService = Executors.newFixedThreadPool(total/limit);
		for(int i=0;i<=total/limit;i++)
		{
			String name="T"+i;
			executorService.execute(new SetIDF(name,i*limit,limit));
		}
		executorService.shutdown();
		while(!executorService.isTerminated()){}
		long end=System.currentTimeMillis();
		System.out.println("total time: "+(end-begin)/1000);
	}