获取分布式缓存数据的最佳方法是什么？

public class TrailMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

    ArrayList<String> globalFreq = new ArrayList<String>();
    public void setup(Context context) throws IOException{
        Configuration conf = context.getConfiguration();
        FileSystem fs = FileSystem.get(conf);
        URI[] cacheFiles = DistributedCache.getCacheFiles(conf);
        Path getPath = new Path(cacheFiles[0].getPath());
        BufferedReader bf = new BufferedReader(new InputStreamReader(fs.open(getPath)));
        String setupData = null;
        while ((setupData = bf.readLine()) != null) {
            String [] parts = setupData.split(" ");
            globalFreq.add(parts[0]);
        }
    }
    public void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {
        //Accessing "globalFreq" data .and do further processing
        }

或

public class TrailMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    URI[] cacheFiles
    public void setup(Context context) throws IOException{
        Configuration conf = context.getConfiguration();
        FileSystem fs = FileSystem.get(conf);
        cacheFiles = DistributedCache.getCacheFiles(conf);

    }
    public void map(LongWritable key, Text value, Context context)
            throws IOException, InterruptedException {
        ArrayList<String> globalFreq = new ArrayList<String>();
        Path getPath = new Path(cacheFiles[0].getPath());
        BufferedReader bf = new BufferedReader(new InputStreamReader(fs.open(getPath)));
        String setupData = null;
        while ((setupData = bf.readLine()) != null) {
            String [] parts = setupData.split(" ");
            globalFreq.add(parts[0]);
        }

        }

所以如果我们像（代码2）那样做，这意味着什么 Say we have 5 map task every map task reads the same copy of the data . 在为每个Map这样写的时候，任务会多次读取数据，对吗（5次）？
代码1：当它在设置中写入时，它被读取一次，全局数据在Map中被访问。
这是编写分布式缓存的正确方法。