code: public static void releaseCache(URI cache, Configuration conf, long timeStamp)
      throws IOException {
      String cacheId = getKey(cache, conf, timeStamp);
  
      synchronized (cachedArchives) {
        CacheStatus lcacheStatus = cachedArchives.get(cacheId);
        if (lcacheStatus == null) {
          LOG.warn("Cannot find localized cache: " + cache +
                   " (key: " + cacheId + ") in releaseCache!");
          return;
        }
        lcacheStatus.refcount--;
      }
    }
docs: This is the opposite of getlocalcache. When you are done with
  using the cache, you need to release the cache
  @param cache The cache URI to be released
  @param conf configuration which contains the filesystem the cache
  is contained in.
  @throws IOException