ConcurrentHashMapCopyOnWriteArrayList ConcurrentHashMap CopyOnWriteArrayList写入时复制适用于读多写少 https://dunwu.github.io/javacore/concurrent/Java%E5%B9%B6%E5%8F%91%E5%92%8C%E5%AE%B9%E5%99%A8.html#_2-%E5%B9%B6%E5%8F%91%E5%AE%B9%E5%99%A8%E7%AE%80%E4%BB%8B
