Double-Checked Locking

[QiAnXinCodeSafe]

octo-rpc/dorado/dorado-registry/dorado-registry-zookeeper/src/main/java/com/meituan/dorado/registry/zookeeper/curator/ZookeeperManager.java

Lines 36 to 41 in f451295

	if (zkClient == null) {
	synchronized (ZookeeperManager.class) {
	zkClient = zkClients.get(address);
	if (zkClient == null) {
	zkClient = new ZookeeperClient(address);
	zkClients.putIfAbsent(address, zkClient);

Double-Checked Locking is widely cited and used as an efficient method for implementing lazy initialization in a multithreaded environment.
Unfortunately, it will not work reliably in a platform independent way when implemented in Java, without additional synchronization.
declares the zkClient field volatile offers a much more elegant solution