code: public void removeMap(String mapId) {
      IndexInformation info = cache.remove(mapId);
      if (info != null) {
        totalMemoryUsed.addAndGet(-info.getSize());
        if (!queue.remove(mapId)) {
          LOG.warn("Map ID" + mapId + " not found in queue!!");
        }
      } else {
        LOG.info("Map ID " + mapId + " not found in cache");
      }
    }
docs: This method removes the map from the cache. It should be called when
  a map output on this tracker is discarded.
  @param mapId The taskID of this map.