@Override
  public void reserveMemory(final long memoryToReserve, AtomicBoolean isStopped) {
    boolean result = reserveMemory(memoryToReserve, true, isStopped);
    if (result) return;
    // Can only happen if there's no evictor, or if thread is interrupted.
    throw new ReserveFailedException(isStopped);
  }
Implementation of memory manager for low level cache. Note that memory is released during
reserve most of the time, by calling the evictor to evict some memory. releaseMemory is
called rarely.
llap-server/src/java/org/apache/hadoop/hive/llap/cache/LowLevelCacheMemoryManager.java