How to prevent spring batch to start new instance of job? - spring-batch

Question

Idea is not to start job if already same job is running.
JobExplorer is simple injected in class where is scheduled method for running
public class JobClass {
private final Job job;
private final JobExplorer jobExplorer;
private final JobLauncher jobLauncher;
public JobMain(Job job,
JobLauncher jobLauncher,
JobExplorer jobExplorer) {
this.job = job;
this.jobLauncher = jobLauncher;
this.jobExplorer = jobExplorer;
}
and then it is executed
#Scheduled("0 */5 * ? * *")
public void startJob() {
JobParameters jobParameters = new JobParametersBuilder()
.addString("jobName", String.valueOf(instant.toEpochMilli()))
.toJobParameters();
jobLauncher.run(job, jobParameters);
}
This is not solution because if JVM stopped while job is running this will be same as current job running:
jobExplorer.findRunningJobExecutions("jobName")
It will find all jobs with exitCode ExitStatus.UNKNOWN.
There is 3 solutions as I see it:
Solution 1:
stop previous running not finished jobs and run new job
PROS: everything is clean, just one property
CONT: loosing current execution of current job
#Scheduled("0 */5 * ? * *")
public void startJob() {
(JobExecution jobExecution: jobExplorer.findRunningJobExecutions("jobName")) jobExecution.stop();
...
}
Solution 2
Calculate time between latest running job like it is here described and if it is any do not start new job:
https://stackoverflow.com/a/23218986/1182625
PROS: everything is clean
CONT: have to have doubled property (5 *60*1000 and "0 */5 * ? * *")
Set<JobExecution> jobExecutions = jobExplorer.findRunningJobExecutions("jobName");
if(jobExecutions.size()>1){
Long currentTime = (new Date()).getTime();
for(JobExecution execution : jobExecutions) {
if((currentTime - execution.getStartTime().getTime()) < 5*60*1000) {
return;
} else {
execution.stop();
}
}
}
Solution 3
Idea is simple to add static (to share between instances of class) volatile (to share between threads) flag which will indicate is any job currently running
PROS: just one property
CONT: needs 2 listeners, and volatile static variable which i don't know how reacted in multi-nodes environment
private static volatile boolean FINISHED = true;
and then simple add listener and FINISHED modify method:
// reset FINISHED after job is done
#AfterJob
public void afterJob() {
FINISHED = true;
}
public void setFinished() {
this.FINISHED = true;
}
And simple add:
#Scheduled("0 */5 * ? * *")
public void startJob() {
if(!FINISHED) return;
FINISHED = false;
...
}
And finally add StepListener
public MyStepListener() {
...
#AfterStep
public ExitStatus afterStep(StepExecution stepExecution) {
if(stepExecution.getExitStatus().getExitCode().equalsIgnoreCase(ExitStatus.FAILED.getExitCode())) (new JobMain()).setFinished();
return null;
}

Answer 1

Ok, I think I go to far with something could be KISS.
Keep It Simple & Stupid.
So, to achieve this is simple to put fixedDelay or fixedStringDelay in #Scheduled annotation if you want to use value from properties file.
#Scheduled(initialDelay = 3*60*1000, fixedDelayString ="${job.fixed_delay}")
With this I achieve that I don't have more than 1 instance of same job at same time.
I only lose that job start at exactly time (like ad midnight or...)

Answer 2

Idea is not to start job if already same job is running.
By design, Spring Batch will prevent that. If you try to start the same job instance while it has a running job execution, you will get a JobExecutionAlreadyRunningException.