[GitHub] [incubator-dubbo] rangtao commented on issue #2435: Summary of several issues of graceful shutdown

[GitHub]

1. 我同意您的说法，Dubbo容器不局限于Spring，可能我描述不太好，目前我们实际应用中使用的容器就是Spring。
2. 确实您没有正面回答我的问题，那么我描述下2.6.3版本停机在如下场景下存在问题：如果应用程序通过停机hook触发，DubboShutDown 
Hook会调用destroyAll方法，因为容器（比如Spring）也通过Hook停机，此时Spirng会提前关闭，可能导致dubbo方法内部无法获取业务Bean。因为多个hook的执行的无序性，destroyAll方法第二次执行会立即返回，所以可能导致容器先摧毁。
3. 关于第三个问题，在2.6.1中ProtocolConfig类中，destroyAll方法包含如下sleep代码。2.6.2中将此部分sleep代码删除了。
2.6.1：
public static void destroyAll() {
        if (!destroyed.compareAndSet(false, true)) {
            return;
        }
        AbstractRegistryFactory.destroyAll();

        // Wait for registry notification
        try {
            **Thread.sleep(ConfigUtils.getServerShutdownTimeout());**
        } catch (InterruptedException e) {
            logger.warn("Interrupted unexpectedly when waiting for registry 
notification during shutdown process!");
        }

        ExtensionLoader<Protocol> loader = 
ExtensionLoader.getExtensionLoader(Protocol.class);
        for (String protocolName : loader.getLoadedExtensions()) {
            try {
                Protocol protocol = loader.getLoadedExtension(protocolName);
                if (protocol != null) {
                    protocol.destroy();
                }
            } catch (Throwable t) {
                logger.warn(t.getMessage(), t);
            }
        }
    }
2.6.2:
    // TODO: 2017/8/30 to move this method somewhere else
    public static void destroyAll() {
        if (!destroyed.compareAndSet(false, true)) {
            return;
        }

        AbstractRegistryFactory.destroyAll();

        ExtensionLoader<Protocol> loader = 
ExtensionLoader.getExtensionLoader(Protocol.class);
        for (String protocolName : loader.getLoadedExtensions()) {
            try {
                Protocol protocol = loader.getLoadedExtension(protocolName);
                if (protocol != null) {
                    protocol.destroy();
                }
            } catch (Throwable t) {
                logger.warn(t.getMessage(), t);
            }
        }
    }

[ Full content available at: 
https://github.com/apache/incubator-dubbo/issues/2435 ]
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