java - Spring batch restrict single instance of job only

Question

I have one spring batch job which can be kicked of by rest URL. I want to make sure only one job instance is allowed to run. and if another instance already running then don't start another. even if the parameters are different.

I searched and found nothing out of box solution. thinking of extending SimpleJobLauncher. to check if any instance of the job running or not.

Answer 1

You could try to intercept the job execution, implementing the JobExecutionListener interface:

public class MyJobExecutionListener extends JobExecutionListener {

    //active JobExecution, used as a lock.
    private JobExecution _active;

    public void beforeJob(JobExecution jobExecution) {
        //create a lock
        synchronized(jobExecution) {
            if(_active!=null && _active.isRunning()) {
                jobExecution.stop();
            } else {
                _active=jobExecution;
            }
        }
    }

    public void afterJob(JobExecution jobExecution) {
          //release the lock
          synchronized(jobExecution) {
              if(jobExecution==_active) {
                _active=null; 
              }
          }
    }
}

And then, inject to the Job definition:

<job id="myJobConfig">
    <listeners>
        <listener ref="myListener"/>
    </listeners>
</job>