How to conditionally enable or disable scheduled jobs in Spring?

Question

I am defining scheduled jobs with cron style patterns in Spring, using the @Scheduled annotation.

The cron pattern is stored in a config properties file. Actually there are two properties files: one default config, and one profile config that is environment dependent (e.g. dev, test, prod customer 1, prod customer 2 etc.) and overrides some of the default values.

I configured a property placeholder bean in my spring context which allows me to use ${} style placeholders to import values from my properties files.

The job beans looks like this:

@Component
public class ImagesPurgeJob implements Job {

    private Logger logger = Logger.getLogger(this.getClass());

    @Override
    @Transactional(readOnly=true)
    @Scheduled(cron = "${jobs.mediafiles.imagesPurgeJob.schedule}")
    public void execute() {
        //Do something
            //can use DAO or other autowired beans here
    }
}

Relevant parts of my context XML :

<!-- Enable configuration of scheduled tasks via annotations -->
    <task:annotation-driven/>

<!-- Load configuration files and allow '${}' style placeholders -->
    <bean class="org.springframework.context.support.PropertySourcesPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:config/default-config.properties</value>
                <value>classpath:config/environment-config.properties</value>
            </list>
        </property>
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="false"/>
    </bean>

I really like this. It's quite simple and clean with minimal XML.

However I have one more requirement: some of these jobs can be totally disabled in some cases.

So, before I used Spring to manage them I created them manually and there is a boolean parameter along with the cron parameter in the config files, to specify if the job has to be enabled or not:

jobs.mediafiles.imagesPurgeJob.enable=true or false
jobs.mediafiles.imagesPurgeJob.schedule=0 0 0/12 * * ?

How can I use this parameter in Spring to conditionally create or just plainly ignore the bean, depending on this config parameter?

One obvious workaround would be to define a cron pattern that would never evaluate, so the job is never executed. But the bean would still be created and the config would be a bit obscure, so I feel there must be a better solution.

Answer 1

@Component
public class ImagesPurgeJob implements Job {

    private Logger logger = Logger.getLogger(this.getClass());

    @Value("${jobs.mediafiles.imagesPurgeJob.enable}")
    private boolean imagesPurgeJobEnable;

    @Override
    @Transactional(readOnly=true)
    @Scheduled(cron = "${jobs.mediafiles.imagesPurgeJob.schedule}")
    public void execute() {

         //Do something
        //can use DAO or other autowired beans here
        if(imagesPurgeJobEnable){

            Do your conditional job here...

        }
    }
}

Answer 2

Spring Boot provides @ConditionalOnProperty, which would be perfect if you were using Spring Boot. This annotation is a specialization of @Conditional, introduced with Spring 4.0.0.

Assuming you're just using "regular" spring and not Spring Boot, you could create your own Condition implementation for use with @Conditional that would mimic Spring Boot's @ConditionalOnProperty.

Answer 3

You can group schedule methods by conditions into number of services and init them like this:

@Service
@ConditionalOnProperty("yourConditionPropery")
public class SchedulingService {

@Scheduled
public void task1() {...}

@Scheduled
public void task2() {...}

}

Answer 4

The most efficient way to disable @Scheduled in Spring is to set cron expression to -

@Scheduled(cron = "-")
public void autoEvictAllCache() {
    LOGGER.info("Refresing the Cache Start :: " + new Date());
    activeMQUtility.sendToTopicCacheEviction("ALL");
    LOGGER.info("Refresing the Cache Complete :: " + new Date());
}

From the docs:

CRON_DISABLED

public static final String CRON_DISABLED
A special cron expression value that indicates a disabled trigger: "-". This is primarily meant for use with ${...} placeholders, allowing for external disabling of corresponding scheduled methods.

Since: 5.1 See Also: ScheduledTaskRegistrar.CRON_DISABLED

Answer 5

If you are looking to toggle @EnableScheduling from a property you can do this in Spring Boot by moving the @EnableScheduling annotation to a configuration class and use @ConditionalOnProperty as follows:

@Configuration
@EnableScheduling
@ConditionalOnProperty(prefix = "com.example.scheduling", name="enabled", havingValue="true", matchIfMissing = true)
public class SchedulingConfiguration {

}

This will disable scheduling for the application. This may be useful in a situation where you want to be able to run the application once or scheduled depending on how it's being started.

From wilkinsona's comment on here: https://github.com/spring-projects/spring-boot/issues/12682

Answer 6

Your question states to condition the actual creation of the bean. You can do this easily with this parameter by using @Profile if you are using at least Spring 3.1.

See the documentation here: http://static.springsource.org/spring/docs/3.1.x/javadoc-api/org/springframework/context/annotation/Profile.html

Answer 7

@Component
public class CurrencySyncServiceImpl implements CurrencySyncService {

    private static Boolean isEnableSync;
    /**
     * Currency Sync FixedDelay in minutes
     */
    private static Integer fixedDelay;

    @Transactional
    @Override
    @Scheduled(fixedDelayString = "#{${currency.sync.fixedDelay}*60*1000}")
    public void sync() {
        if(CurrencySyncServiceImpl.isEnableSync) {
            //Do something
            //you can use DAO or other autowired beans here.
        }
    }

    @Value("${currency.sync.fixedDelay}")
    public void setFixedDelay(Integer fixedDelay) {
        CurrencySyncServiceImpl.fixedDelay = fixedDelay;
    }

    @Value("${currency.sync.isEnable}")
    public void setIsEnableSync(Boolean isEnableSync) {
        CurrencySyncServiceImpl.isEnableSync = isEnableSync;
    }
}

Answer 8

You can also create a Bean based on condition and that Bean can have a Scheduled method.

@Component
@Configuration
@EnableScheduling
public class CustomCronComponent {
    @Bean
    @ConditionalOnProperty(value = "my.cron.enabled", matchIfMissing = true, havingValue = "true")
    public MyCronTask runMyCronTask() {
        return new MyCronTask();
    }
}

and

@Component
public class MyCronTask {
    @Scheduled(cron = "${my.cron.expression}")
    public void run() {
        String a = "";
    }
}

Answer 9

Please see my answer in another question. I think this is the best way to solve it. How to stop a scheduled task that was started using @Scheduled annotation?

Define a custom annotation like below.

@Documented
@Retention (RUNTIME)
@Target(ElementType.TYPE)
public @interface ScheduledSwitch {
    // do nothing
}

Define a class implements org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.

public class ScheduledAnnotationBeanPostProcessorCustom 
    extends ScheduledAnnotationBeanPostProcessor {

    @Value(value = "${prevent.scheduled.tasks:false}")
    private boolean preventScheduledTasks;

    private Map<Object, String> beans = new HashMap<>();

    private final ReentrantLock lock = new ReentrantLock(true);

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) {
        ScheduledSwitch switch = AopProxyUtils.ultimateTargetClass(bean)
            .getAnnotation(ScheduledSwitch.class);
        if (null != switch) {
            beans.put(bean, beanName);
            if (preventScheduledTasks) {
                return bean;
            }
        }
        return super.postProcessAfterInitialization(bean, beanName);
    }

    public void stop() {
        lock.lock();
        try {
            for (Map.Entry<Object, String> entry : beans.entrySet()) {
                postProcessBeforeDestruction(entry.getKey(), entry.getValue());
            }
        } finally {
            lock.unlock();
        }
    }

    public void start() {
        lock.lock();
        try {
            for (Map.Entry<Object, String> entry : beans.entrySet()) {
                if (!requiresDestruction(entry.getKey())) {
                    super.postProcessAfterInitialization(
                        entry.getKey(), entry.getValue());
                }
            }
        } finally {
            lock.unlock();
        }
    }

}

Replace ScheduledAnnotationBeanPostProcessor bean by the custom bean in configuration.

@Configuration
public class ScheduledConfig {

    @Bean(name = TaskManagementConfigUtils.SCHEDULED_ANNOTATION_PROCESSOR_BEAN_NAME)
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    public ScheduledAnnotationBeanPostProcessor scheduledAnnotationBeanPostProcessor() {
        return new ScheduledAnnotationBeanPostProcessorCustom();
    }

}

Add @ScheduledSwitch annotation to the beans that you want to prevent or stop @Scheduled tasks.

Answer 10

I know my answer is a hack, but giving a valid cron expression that never executes may fix the issue (in the environment specific configuration), Quartz: Cron expression that will never execute

Answer 11

We can disable the bean creation of the class having that scheduled methods using @Conditional annotation. This is very similar to @ConditionalOnProperty. This is used to conditionally spin up a bean on to the spring context. If we set the value to false, then the bean will not be spun up and loaded to spring. Below is the code.

application.properties:

    com.boot.enable.scheduling=enable

Condition:

public class ConditionalBeans implements Condition {
    @Override
    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        return "enabled".equalsIgnoreCase(context.getEnvironment().getProperty("com.boot.enable.scheduling"));
    }
}

My schedule class

@Service
@Conditional(ConditionalSchedules.class)
public class PrintPeriodicallyService {

    @Scheduled(fixedRate = 3000)
    public void runEvery3Seconds() {
        System.out.println("Current time : " + new Date().getTime());
    }
}

This approach has a lot of flexibility where the condition generation is totally under our control.