When user creates a TaskScheduler the application context can blow up #3508
Description
The way that @EnableScheduling works can be surprising for users. The problem is that it uses bean lookup by type for TaskScheduler (and TaskExecutor) by default, and if the context contains more than one there is no strategy to fall back to a safe place (e.g. a well-known bean name). Thus this app blows up in your face when Spring Integration is on the classpath:
@SpringBootApplication
public class DemoApplication {
private static Log logger = LogFactory.getLog(DemoApplication.class);
@Scheduled(fixedDelay=2000)
public void work() {
logger.info("Hello");
}
@Bean
public TaskScheduler myTaskScheduler() {
return new ThreadPoolTaskScheduler();
}
...
}whereas this one is fine:
@SpringBootApplication
public class DemoApplication {
private static Log logger = LogFactory.getLog(DemoApplication.class);
@Scheduled(fixedDelay=2000)
public void work() {
logger.info("Hello");
}
...
}Spring Integration exacerbates the problem, but actually what they do is pretty sensible (look for a bean with a well known name "taskScheduler" and use that if there is a conflict).
Corollary: the app works if the @Bean is called "taskScheduler" as well:
@SpringBootApplication
public class DemoApplication {
private static Log logger = LogFactory.getLog(DemoApplication.class);
@Scheduled(fixedDelay=2000)
public void work() {
logger.info("Hello");
}
@Bean
public TaskScheduler taskScheduler() {
return new ThreadPoolTaskScheduler();
}
...
}