Java Spring @Scheduled tasks executing twice

Question

I have a simple test method here that is set to run every 5 seconds and it does, but looking at the System.out you can see it appears to be doing something odd.

Answer 1

I know the answer!!

Don't init your Scheduled twice

Loot at your web log :

WebApplicationContext once and servlet once

so in your servlet.xml don't do like this

import resource="classpath:applicationContext.xml"

Answer 2

If you look at the documentation, there is a note that explicitly calls out this phenomenon.

The note is under section 25.5.1 at this link, and reads:

Make sure that you are not initializing multiple instances of the same @Scheduled annotation class at runtime, unless you do want to schedule callbacks to each such instance. Related to this, make sure that you do not use @Configurable on bean classes which are annotated with @Scheduled and registered as regular Spring beans with the container: You would get double initialization otherwise, once through the container and once through the @Configurable aspect, with the consequence of each @Scheduled method being invoked twice.

I understand that this is merely suggestion at this point, but I do not think we have enough information to diagnose the issue further.

Answer 3

Had the same issue with my springboot-application, the Scheduler runs twice.

Reason was, as mentioned multiple times in earlier comments, that the bean is initialized multiple times.

My solution was:

• Remove the @Component Annotation (on the Class which contains the @Scheduled method)
• Manually add the Class which contains the @Scheduled Method into the ApplicationContext

In the code- this was the change i´ve made:

// @Component <------ Removed
public class FileTransferScheduler {

    private final Logger logger = LoggerFactory.getLogger(FileTransferScheduler.class);

    @Autowired
    private ExtractorService extractorService;

    @Scheduled(cron = "* /1 * * * *")
    public void scheduleFileTransfer() {

        logger.info("Triggered cronjob to transfer new uploads to dms...");
        extractorService.extractTmcUploads();
    }

}

...and then this change in the main method of the springboot-application:

@EnableScheduling
@SpringBootApplication
public class InsidersExtractorApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        // The Scheduler Class needs to be added manually, because it dont have to be defined as Bean
        return application.sources(InsidersExtractorApplication.class, FileTransferScheduler.class);
    }

    public static void main(String[] args) {
        SpringApplication.run(InsidersExtractorApplication.class, args);
    }

}

Answer 4

it is happening because of context listener

Just remove

< listener >

< listener-class >org.springframework.web.context.ContextLoaderListener< /listener-class >

< /listener >

from web.xml it should work.

Answer 5

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
         /WEB-INF/spring/root-context.xml
         /WEB-INF/spring/security/spring-security.xml
         /WEB-INF/spring/mongo/mongo-config.xml
         /WEB-INF/spring/appServlet/spring-context.xml
    </param-value>
</context-param>
<servlet>
    <servlet-name>appServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/appServlet/spring-context.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

That is my web.xml . So , you can see that "/WEB-INF/spring/appServlet/spring-context.xml" is loaded twice (once in context-param , once in servlet -> init-param ).

Answer 6

I had the same problem, I tried all the suggested methods and nothing worked for me. Finally I was able to find the solution by removing the extension to 'SpringBootServletInitializer' and the 'configure' method of my WebApplication class and with this I stopped duplicating my Scheduled Task.