When using spring cloud[Dalston.SR1] version to develop timing job, it is found that the job has been executed twice;
In the following log, it is found that a job is executed by two workers (task-scheduler-1 and task-scheduler-2) in a task scheduler pool, which is strange;

2018-02-23 14:28:30.001 [task-scheduler-2] INFO  c.k.micro.cfca.scheduled.ContractSealApplyJob - ==Callback job==start==
2018-02-23 14:28:30.002 [task-scheduler-2] INFO  c.k.micro.cfca.scheduled.ContractSealApplyJob - ==Callback job==End==
2018-02-23 14:28:30.003 [task-scheduler-1] INFO  c.k.micro.cfca.scheduled.ContractSealApplyJob - ==Callback job==start==
2018-02-23 14:28:30.003 [task-scheduler-1] INFO  c.k.micro.cfca.scheduled.ContractSealApplyJob - ==Callback job==End==

log is added to the constructor to confirm that the class is loaded only once;

Example code:

@RefreshScope
@Component
@EnableScheduling
public class ContractSealApplyJob{

	@Value("${value1}")
	private String value1;

	/**
     * Make callback job
     */
    @Scheduled(cron = "${0/30 * * * * *}")//Every 30 seconds
    public void doCallBack(){
		logger.info("==Callback job==start==");
		....
		logger.info("==Callback job==End==");
	}
}

It is found that the @ RefreshScope annotation in spring cloud config causes it; the correct usage is to put the configuration item into a Config class; then inject it into the Job. @The class annotated by RefreshScope will regenerate a new instance after refreshing at runtime; however, the above Job is not re instantiated (not refreshed), but put the Job into the pool twice.

/**
 * Convenience annotation to put a <code>@Bean</code> definition in
 * {@link org.springframework.cloud.context.scope.refresh.RefreshScope refresh scope}.
 * Beans annotated this way can be refreshed at runtime and any components that are using
 * them will get a new instance on the next method call, fully initialized and injected
 * with all dependencies.
 * 
 * @author Dave Syer
 *
 */
@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Scope("refresh")
@Documented
public @interface RefreshScope {
	/**
	 * @see Scope#proxyMode()
	 */
	ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;

}

@There are other pits for RefreshScope, see http://www.cnblogs.com/yjmyzz/p/8085530.html for details