@Override
  public String toString() {
    return "MemoryManager{"
        + "name="
        + name
        + ", enabled="
        + enabled
        + ", totalMemorySizeInBytes="
        + totalMemorySizeInBytes
        + ", allocatedMemorySizeInBytes="
        + allocatedMemorySizeInBytes
        + '}';
  }
Get actual used memory size in bytes of memory manager
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/memory/MemoryManager.java