@RefreshScope停止@定时任务

Question

我有一个监控应用程序，其中我正在运行一个fixedRate任务。这是通过Consul配置的配置参数。我想引入更新的配置，所以我添加了@RefreshScope。但是，只要我更新Consul上的配置值，fixedRate任务就会停止运行。

@Service
@RefreshScope
public class MonitorService {

    @Autowired
    private AppConfig appConfig;

    @PostConstruct
    public void postConstRun() {
        System.out.println(appConfig.getMonitorConfig());
    }

    @Scheduled(fixedRate = 1000)
    public void scheduledMonitorScan() {
        System.out.println("MonitorConfig:" + appConfig.getMonitorConfig());
    }
}

AppConfig类只有一个字符串参数：

@Configuration
@Getter
@Setter
public class AppConfig {

    @Value("${monitor-config:default value}")
    private String monitorConfig;
}

一旦我更新了consul中的值，计划任务就停止运行(在sheduledMonitorScan方法中显示)停止显示。

Answer 1

下面是我们解决这个问题的方法。

/**
 * Listener of Spring's lifecycle to revive Scheduler beans, when spring's
 * scope is refreshed.
 * <p>
 * Spring is able to restart beans, when we change their properties. Such a
 * beans marked with RefreshScope annotation. To make it work, spring creates
 * <b>lazy</b> proxies and push them instead of real object. The issue with
 * scope refresh is that right after refresh in order for such a lazy proxy
 * to be actually instantiated again someone has to call for any method of it.
 * <p>
 * It creates a tricky case with Schedulers, because there is no bean, which
 * directly call anything on any Scheduler. Scheduler lifecycle is to start
 * few threads upon instantiation and schedule tasks. No other bean needs
 * anything from them.
 * <p>
 * To overcome this, we had to create artificial method on Schedulers and call
 * them, when there is a scope refresh event. This actually instantiates.
 */
@RequiredArgsConstructor
public class RefreshScopeListener implements ApplicationListener<RefreshScopeRefreshedEvent> {
    private final List<RefreshScheduler> refreshSchedulers;

    @Override
    public void onApplicationEvent(RefreshScopeRefreshedEvent event) {
        refreshSchedulers.forEach(RefreshScheduler::materializeAfterRefresh);
    }
}

因此，我们定义了一个接口，它不做任何特别的事情，但允许我们调用一个刷新的作业。

public interface RefreshScheduler {
    /**
     * Used after refresh context for scheduler bean initialization
     */
    default void materializeAfterRefresh() {
    }
}

这是实际的job，它的参数from.properties可以刷新。

public class AJob implements RefreshScheduler {
    @Scheduled(cron = "${from.properties}")
    public void aTask() {
        // do something useful
    }
}

更新:当然，AJob bean必须在@Configuration中标记为@RefreshScope

@Configuration
@EnableScheduling
public class SchedulingConfiguration {
    @Bean
    @RefreshScope
    public AJob aJob() {
        return new AJob();
    }
}

Answer 2

我使用RefreshScopeRefreshedEvent成功地从consul config server获取并覆盖了这些值

import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.cloud.context.scope.refresh.RefreshScopeRefreshedEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
@RefreshScope
public class AlertSchedulerCron implements ApplicationListener<RefreshScopeRefreshedEvent> {

    private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Value("${pollingtime}")
    private String pollingtime;
    
    /*
     * @Value("${interval}") private String interval;
     */
    @Scheduled(cron = "${pollingtime}")
    //@Scheduled(fixedRateString = "${interval}" )
    public void task() {

        System.out.println(pollingtime);
        System.out.println("Scheduler (cron expression) task with duration : " + sdf.format(new Date()));
    }

    @Override
    public void onApplicationEvent(RefreshScopeRefreshedEvent event) {
        // TODO Auto-generated method stub
        
    }

    
}

Answer 3

我已经通过实现SchedulingConfigurer接口解决了这种情况。在这里，我从外部属性文件中动态更新"scheduler.interval“属性，即使在执行器刷新之后，调度器也能正常工作，因为我不再使用@ refresh anymore。希望这也能对你的情况有所帮助。

public class MySchedulerImpl implements SchedulingConfigurer {

    @Autowired
    private Environment env;

    @Bean(destroyMethod = "shutdown")
    public Executor taskExecutor() {
        return Executors.newScheduledThreadPool(10);
    }

    @Override
    public void configureTasks(final ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(this.taskExecutor());
        taskRegistrar.addTriggerTask(() -> {
            //put your code here that to be scheduled
        }, triggerContext -> {
            final Calendar nextExecutionTime = new GregorianCalendar();
            final Date lastActualExecutionTime = triggerContext.lastActualExecutionTime();

            if (lastActualExecutionTime == null) {
                nextExecutionTime.setTime(new Date());
            } else {
                nextExecutionTime.setTime(lastActualExecutionTime);
                nextExecutionTime.add(Calendar.MILLISECOND, env.getProperty("scheduler.interval", Integer.class));
            }
            return nextExecutionTime.getTime();
        });
    }
}