[Discuss] Shall we change Nacos-Client naming listener notify way (sync -> async)

[horizonzy]

Describe the topc
Now in com.alibaba.nacos.client.naming.core.EventDispatcher.Notifier.run, when get serviceChange from server, it will notify com.alibaba.nacos.client.naming.core.EventDispatcher.Notifier.run, find listener by serviceKey, and execute the callback.
But the callback is sync to execute, if some long time operation in the callback, it will blocking other service's notify.
Shall we add some info in docs to hint user, this callback is sync, if do long time operation, it will influence other listener or service to notify. let user execute it by thread they defined by themselves.
Or execute callback in thread pool which realized by framework.

[chuntaojun]

You can use NotifyCenter instead, which is already in the common module

[horizonzy]

I mean this logic

[chuntaojun]

In the end, all event mechanisms need to be gathered into NotifyCenter. The logic you want has been implemented internally. You can see

[chuntaojun]

@Override
public void notifySubscriber(final Subscriber subscriber, final Event event) {
        
        LOGGER.debug("[NotifyCenter] the {} will received by {}", event, subscriber);
        
        final Runnable job = new Runnable() {
            @Override
            public void run() {
                subscriber.onEvent(event);
            }
        };
        
        final Executor executor = subscriber.executor();
        
        if (executor != null) {
            executor.execute(job);
        } else {
            try {
                job.run();
            } catch (Throwable e) {
                LOGGER.error("Event callback exception : {}", e);
            }
        }
}

[horizonzy]

yeah, 👍