code: public void shutdown() {
      for (Map.Entry<OFileMMap, OMMapBufferEntry[]> entries : bufferPoolPerFile.entrySet()) {
        OFileMMap file;
        file = entries.getKey();
        lockManager.acquireLock(Thread.currentThread(), file, OLockManager.LOCK.EXCLUSIVE);
        try {
          removeFileEntries(entries.getValue());
        } finally {
          lockManager.releaseLock(Thread.currentThread(), file, OLockManager.LOCK.EXCLUSIVE);
        }
      }
      bufferPoolPerFile.clear();
      mapEntrySearchInfo.clear();
    }
docs: {@inheritDoc}
  <p/>
  Removes mapped entries for all existing files.