Put some delay between two batch jobs

Question

I have created two batch jobs and both jobs have initial delay of 20 seconds. Now I want to put some delay between those 2 jobs. If Job1 is running then Job2 has to wait for some seconds and then execute only if Job1 is done similarly if Job2 is running then Job1 has to wait for some seconds and then execute only if Job2 is done.

@Component
public class Job1{

    @Scheduled(fixedRate = 20000)
    public void execute() {
        //business logic
    }
}

@Component
public class Job2{

    @Scheduled(fixedRate = 20000)
    public void execute() {
        //business logic
    }
}

Answer 1

You can achieve the behaviour by having the jobs run in a single synchronized method, for example by introducing a class which has a method to execute a synchronized method, i.e.

@Component
class SingleThreadJobRunner {
    synchronized void run(Runnable runnable) {
        runnable.run();
    }
}

A full working example which utilizes this class across different @Scheduled-methods:

@EnableScheduling
@SpringBootApplication
public class Test {
    public static void main(String[] args) {
        SpringApplication.run(Test.class, args);
    }
}

@Component
class SingleThreadJobRunner {
    synchronized void run(Runnable runnable) {
        runnable.run();
    }
}

@Component
@RequiredArgsConstructor
class Job1 {
    private final SingleThreadJobRunner singleThreadJobRunner;

    @Scheduled(fixedRate = 1000)
    public void execute() {
        singleThreadJobRunner.run(() -> {
            System.out.print("job 1 started - ");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            System.out.println("job 1 completed");

        });
    }
}

@Component
@RequiredArgsConstructor
class Job2 {
    private final SingleThreadJobRunner singleThreadJobRunner;

    @Scheduled(fixedRate = 1500)
    public void execute() {
        singleThreadJobRunner.run(() -> {
            System.out.print("job 2 started - ");
            try {
                Thread.sleep(300);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            System.out.println("job 2 completed");
        });
    }
}

Varying rates and sleep-times were used to show that the jobs never overlap. If you need the delay between the methods which you mention in your question, this could be added to the run()-method.

Answer 2

This is how I solved the issue. called the business logic inside a synchronized block so both the job can't run in parallel.

If Job1 is running then Job2 will wait for some seconds and then execute only if Job1 is done similarly if Job2 is running then Job1 will wait for some seconds and then execute only if Job2 is done.

@Component
public class Job1{

    @Autowired
    private ISyncExecuteService syncExecuteService;

    @Scheduled(fixedRate = 20000)
    public void execute() {
       syncExecuteService.execute("job1");
    }
}

@Component
public class Job2{

    @Autowired
    private ISyncExecuteService syncExecuteService;

    @Scheduled(fixedRate = 20000)
    public void execute() {
        syncExecuteService.execute("job2");
    }
}

@Component
public class SyncExecuteServiceImpl implements ISyncExecuteService{
    @Override
    public void execute(String jobType) {
        synchronized (this) {
            if (jobType.equals("job1")) {
                executeJob1();
            } else if (jobType.equals("job2")){
                executeJob2();
            }
        }
    }

    private void executeJob1(){
        //business logic for batch job 1;
    }

    private void executeJob2(){
        //business logic for batch job 2;
    }
}