优雅停机-东拼西凑

dubbo优雅停机：

背景：dubbo消费者请求时候，遭遇 停机发布 （springboot） ：on consumer 10.0.xxx.xxx use dubbo version 2.6.0 is DESTROYED, can not be invoked any more

销毁流程：

com.alibaba.dubbo.config.ProtocolConfig#destroyAll

注册中心删除server节点 ：Registry  

AbstractRegistryFactory.destroyAll()

协议/流程：Protocol

ExtensionLoader<Protocol> loader = ExtensionLoader.getExtensionLoader(Protocol.class);
Iterator i$ = loader.getLoadedExtensions().iterator();

while(i$.hasNext()) {
    String protocolName = (String)i$.next();

    try {
        Protocol protocol = (Protocol)loader.getLoadedExtension(protocolName);
        if (protocol != null) {
            protocol.destroy();
        }
    } catch (Throwable var4) {
        logger.warn(var4.getMessage(), var4);
    }
}