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

Spring 4.x

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.

Spring Boot

In Spring Boot there is a simple property to configure the thread pool size:

spring.task.scheduling.pool.size=5