code: public static void purgeCache(Configuration conf,
        MRAsyncDiskService service) throws IOException {
      synchronized (cachedArchives) {
        LocalFileSystem localFs = FileSystem.getLocal(conf);
        for (Map.Entry<String,CacheStatus> f: cachedArchives.entrySet()) {
          try {
            deleteLocalPath(service, localFs, f.getValue().localizedLoadPath);
          } catch (IOException ie) {
            LOG.debug("Error cleaning up cache", ie);
          }
        }
        cachedArchives.clear();
      }
    }
docs: Clear the entire contents of the cache and delete the backing files. This
  should only be used when the server is reinitializing, because the users
  are going to lose their files.