@Override
    public void run() {
      lru.evict();
    }
The cache for mob files. This cache doesn't cache the mob file blocks. It only caches the
references of mob files. We are doing this to avoid opening and closing mob files all the time.
We just keep references open.
hbase-server/src/main/java/org/apache/hadoop/hbase/mob/MobFileCache.java