• Dubbo version: 2.5.9
• Operating System version: Suse Linux 11
• Java version: 1.8

Steps to reproduce this issue

1. write a project that is a provider side exposed serviceA and in the service implimentation invokes another remote service serviceB. The invoke code is like this SpringContainer.getContext().getBean("ref");
2. continious request from outside for the serviceA (many node for serviceA)
3. stop one serviceA node
4. start the stopped serviceA node
5. almost every time first one or two serviceA invoke failed, exception is NullPointerException, occurred for SpringContainer.getContext();

Reason: dubbo service is exposed with spring container ContextRefreshedEvent。 but that moment SpringContainer.getContext() is not started, if it is ContextStartedEvent, this bug will be fixed.