hikari pool μλ private final ConcurrentBag<PoolEntry> connectionBag; μ΄ μλ€.
PoolEntry λ₯Ό λ§λ€κ³ connectionBag μ add νλ€.
connectionBag μλ private final CopyOnWriteArrayList<T> sharedList; κ° μλ€.
μλ§ μ°λ λμ μν΄ μμ±λλ weaked list μΈ λ― νλ€