Hadoop DistributedCache is deprecated - what is the preferred API?

Question

My map tasks need some configuration data, which I would like to distribute via the Distributed Cache.

The Hadoop MapReduce Tutorial shows the usage of the DistributedCache class, roughly as follows:

// In the driver JobConf conf = new JobConf(getConf(), WordCount.class); ... DistributedCache.addCacheFile(new Path(filename).toUri(), conf);   // In the mapper Path[] myCacheFiles = DistributedCache.getLocalCacheFiles(job); ... 

However, DistributedCache is marked as deprecated in Hadoop 2.2.0.

What is the new preferred way to achieve this? Is there an up-to-date example or tutorial covering this API?

Answer 1

The APIs for the Distributed Cache can be found in the Job class itself. Check the documentation here: http://hadoop.apache.org/docs/stable2/api/org/apache/hadoop/mapreduce/Job.html The code should be something like

Job job = new Job(); ... job.addCacheFile(new Path(filename).toUri()); 

In your mapper code:

Path[] localPaths = context.getLocalCacheFiles(); ...