private void flush() {
      heapLock.lock();
      try {
        doNotifyUnderHeapLock(count, buffers);
      } finally {
        count = 0;
        heapLock.unlock();
      }
    }
Wraps around the structures used in thread locals and buffers instances of LlapCachableBuffers in order to prevent
lock contention in LRFU during buffer ingress initiated heap access.
llap-server/src/java/org/apache/hadoop/hive/llap/cache/LowLevelLrfuCachePolicy.java