How to poll BatchStatus for an executing job?

I have a batch job which has to be repeated for a list of items. So I have a "parent" job which uses a batchlet step to load the list and start a child job for each id in the list. Each child job is launched using JobOperator and param using Properties class and this works fine as expected.

I have to retrieve the batch status and wait for the child job to be completed, in order to iterate through the list. I'm trying to get the batch status or exit status using the JobExecution class, however the JobExecution is not retrieving the batch status for the child job.

Instead, I always see the batch status of STARTED, even after the child job completes.

My code looks like:

for (int i = 1; i <= rsList; i++) {
            long execId = jobOperator.start("gah-history-chunk-archive-job",jobParamProperties);
            JobInstance jobInstance = jobOperator.getJobInstance(execId);
            JobExecution jobExecution = jobOperator.getJobExecution(execId);
            logger.info("Instance id: "+jobInstance.getInstanceId());
            while(!jobExecution.getBatchStatus().toString().equals("COMPLETED") || !jobExecution.getBatchStatus().toString().equals("FAILED")) {
                //Both batch status and exit status giving the status of this batchlet, not giving the status of gah-history-chunk-archive-job
logger.info("Batch status is: "+jobExecution.getBatchStatus() +" Thread is sleeping for 5 seconds");
                logger.info("Exit status:"+jobExecution.getExitStatus());

                Thread.sleep(300);
            }
        }

I want to know, how to retrieve batch or exit status of the child job launched from the batchlet. Why do I continue to see a BatchStatus of STARTED?

Solution

To "poll" the status of a JobExecution you should obtain a new instance from the JobOperator each time you check its status. So get the JobExecution inside the while-loop, NOT outside.

So it should be more like, for example:

do {
  Thread.sleep(300);

  // log or whatever

  BatchStatus status = jobOperator.getJobExecution(execId).getBatchStatus();

}  while(status != BatchStatus.COMPLETED && status != BatchStatus.FAILED) ;

This is a bit tricky because the behavior here is not standardized by the specification.
Because the spec allows for a diversity of job repository implementations (e.g. database, simple in-memory map, other, ...), it doesn't require a specific behavior for a "cached" JobExecution, and you may find that it "works" some of the time with your original code.

I don't think that what you are actually seeing is the "parent" object instance being returned; I suspect you may just be getting confused by not seeing what you expected.

In any case, to have your code be more portable, obtain the JobExecution with each status check.