void MemoryService::add_psYoung_memory_pool(PSYoungGen* gen, MemoryManager* major_mgr, MemoryManager* minor_mgr) {

  {- -------------------------------------------
  (1) EdenMutableSpacePool と SurvivorMutableSpacePool のインスタンスを生成し, 
      引数で与えられた MemoryManager, 及び _pools_list に登録する.
      ---------------------------------------- -}

      assert(major_mgr != NULL && minor_mgr != NULL, "Should have two managers");

      // Add a memory pool for each space and young gen doesn't
      // support low memory detection as it is expected to get filled up.
      EdenMutableSpacePool* eden = new EdenMutableSpacePool(gen,
                                                            gen->eden_space(),
                                                            "PS Eden Space",
                                                            MemoryPool::Heap,
                                                            false /* support_usage_threshold */);

      SurvivorMutableSpacePool* survivor = new SurvivorMutableSpacePool(gen,
                                                                        "PS Survivor Space",
                                                                        MemoryPool::Heap,
                                                                        false /* support_usage_threshold */);

      major_mgr->add_pool(eden);
      major_mgr->add_pool(survivor);
      minor_mgr->add_pool(eden);
      minor_mgr->add_pool(survivor);
      _pools_list->append(eden);
      _pools_list->append(survivor);
    }