MemoryPool* MemoryService::add_survivor_spaces(DefNewGeneration* gen,
                                               const char* name,
                                               bool is_heap,
                                               size_t max_size,
                                               bool support_usage_threshold) {

  {- -------------------------------------------
  (1) SurvivorContiguousSpacePool のインスタンスを生成し, _pools_list に登録する.
      ---------------------------------------- -}

      MemoryPool::PoolType type = (is_heap ? MemoryPool::Heap : MemoryPool::NonHeap);
      SurvivorContiguousSpacePool* pool = new SurvivorContiguousSpacePool(gen, name, type, max_size, support_usage_threshold);

      _pools_list->append(pool);
      return (MemoryPool*) pool;
    }