[SOLVED] Java Spring @Scheduled Cron Task

Issue

I am currently bumping into an issue whilst using the @Scheduled (cron) annotation in Spring.

@Scheduled(cron = "0 0 3 * * MON-FRI", zone = "Europe/Berlin")

This task executes every day at 3 o'clock in the morning (Monday-Friday):

• 03:00:00,278 - 03:00:08,269
• 03:00:08,269 - 03:00:15,451

My question is, why does this task execute twice? I have stated that it should only run at minute "0" and "0" seconds, but this seems off (see execution times). I have two such tasks and both have this issue. Is there anybody that may know the reason on why this is happening and how to avoid it?

I am using Spring Boot Version 2.1.6. Note: will be upgrading to Version 2.7 soon.

Edit:

My scheduler class:

@Component
@RequiredArgsConstructor
@Log4j2
public class LdapTask {

    private final IAppUserService appUserService;
    
    private final IEmployeeService employeeService;
    
    //second, minute, hour, day of month, month, day(s) of week
    @Scheduled(cron = "0 0 3 * * MON-FRI", zone = "Europe/Berlin")
    public void blockAppUsers() {
        /* Logic here */
    }
    
    @Scheduled(cron = "0 20 3 * * MON-FRI")
    public void checkEmailAddresses() {
        /* Logic here */
    }
}

Application (Entry for this application):

@SpringBootApplication(exclude = MultipartAutoConfiguration.class)
@EntityScan(basePackages = "...")
@EnableScheduling
public class Application extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }
    
    public static void main(String[] args) {
         SpringApplication.run(Application.class, args);
    }
}

Answer for my problem:

I replaced the overridden method configure from SpringBootServletInitializer body with this:

@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class, LdapTask.class);
}

instead of:

@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
}

and removing the @Component Annotation in the LdapTask Class.

As the answer of this post hinted, spring was actually creating two instances of the ApplicationContext, which executed this method twice.

Solution

Check carefully logs when initializing application.

Most likely, your scheduler been is initialized twice. One of the reasons may be extending from SpringBootServletInitializer - it may initialize beans once for WebApplicationContext, and once more for Servlet context.

source

P.S. to give you the solution I would need acces to whole src code, as it may even be an extra starter dependency in pom

Answered By - Maksym Rudenko

Answer Checked By - Willingham (WPSolving Volunteer)