Websocket + Redis Session = java.lang.IllegalStateException: Unexpected use of scheduler.

[nagyzsolthun]

When using spring-boot-starter-websocket together with spring-session-data-redis and Jedis I see this exception at startup. Example project: https://github.com/nagyzsolthun/spring-websocket-redis-exception

java.lang.IllegalStateException: Unexpected use of scheduler.
at org.springframework.web.socket.config.annotation.WebSocketConfigurationSupport$NoOpScheduler.schedule(WebSocketConfigurationSupport.java:108) ~[spring-websocket-5.0.5.RELEASE.jar:5.0.5.RELEASE]
...

How to use Spring Websocket with Spring Redis?

[snicoll]

@EnableWebSocket with no further configuration might create a no op scheduler which will conflict with any other use of a task scheduler.

This is the second time that we see that issue and I think this should be addressed in Spring Framework. Paging @rstoyanchev for feedback.

@nagyzsolthun Thanks for the sample.Cconfiguring the task scheduler yourself is a workaround for now, I'll submit a PR to your sample shortly.

[wilkinsona]

Here's the complete stack:

java.lang.IllegalStateException: Unexpected use of scheduler.
        at org.springframework.web.socket.config.annotation.WebSocketConfigurationSupport$NoOpScheduler.schedule(WebSocketConfigurationSupport.java:108) ~[spring-websocket-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleCronTask(ScheduledTaskRegistrar.java:414) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.config.ScheduledTaskRegistrar.scheduleTasks(ScheduledTaskRegistrar.java:352) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.config.ScheduledTaskRegistrar.afterPropertiesSet(ScheduledTaskRegistrar.java:332) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:280) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:211) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:102) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:400) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:354) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:888) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:161) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553) ~[spring-context-5.0.5.RELEASE.jar:5.0.5.RELEASE]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.1.RELEASE.jar:2.0.1.RELEASE]
        at my.example.MyApp.main(MyApp.java:13) [main/:na]

[snicoll]

@nagyzsolthun I've submitted a PR to your project.

I think that we should try to find a way to avoid registering a broken TaskScheduler to the context. I've created SPR-16705