Does spring @Scheduled annotated methods runs on different threads?

Question

I have several methods annotated with @Scheduled(fixedDelay=10000).

In the application context, I have this annotation-driven setup:

<task:annotation-driven /> 

The problem is, sometimes some of the method executions get delayed by seconds and even minutes.

I'm assuming that even if a method takes a while to finish executing, the other methods would still execute. So I don't understand the delay.

Is there a way to maybe lessen or even remove the delay?

Answer 1

The documentation about scheduling says:

If you do not provide a pool-size attribute, the default thread pool will only have a single thread.

So if you have many scheduled tasks, you should configure the scheduler, as explained in the documentation, to have a pool with more threads, to make sure one long task doesn't delay all the other ones.

Answer 2

For completeness, code below shows the simplest possible way to configure scheduler with java config:

@Configuration @EnableScheduling public class SpringConfiguration {      @Bean(destroyMethod = "shutdown")     public Executor taskScheduler() {         return Executors.newScheduledThreadPool(5);     }     ... 

When more control is desired, a @Configuration class may implement SchedulingConfigurer.