Spring batch A job instance already exists

Question

OK,

I know this has been asked before, but I still can't find a definite answer to my question. And my question is this: I am using spring batch to export data to SOLR search server. It needs to run every minute, so I can export all the updates. The first execution passes OK, but the second one complains with:

2014-10-02 20:37:00,022 [defaultTaskScheduler-1] ERROR: catching
org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException: A job     instance already exists and is complete for parameters={catalogVersionPK=3378876823725152,
type=UPDATE}.  If you want to run this job again, change the parameters.
    at org.springframework.batch.core.repository.support.SimpleJobRepository.createJobExecution(SimpleJobRepository.java:126)
    at 

Of course I can add a date-time parameter to the job like this:

.addLong("time", System.getCurrentTimeMillis())

and then the job can be run more than once. However, I also want to query the last execution of the job, so I have code like this:

DateTime endTime = new DateTime(0);
JobExecution je = jobRepository.getLastJobExecution("searchExportJob", new JobParametersBuilder().addLong("catalogVersionPK", catalogVersionPK).addString("type", type).toJobParameters());
if (je != null && je.getEndTime() != null) {
   endTime = new DateTime(je.getEndTime());
}

and this returns nothing, because I didn't provide the time parameter. So seems like I can run the job once and get the last execution time, or i can run it multiple times and not get the last execution time. I am really stuck :(

Answer 1

Use the Job Explorer as suggested by Luca Basso Ricci.

Because you do not know the job parameters you need to look up by instance.

1. Look for the last instance of job named searchExportJob
2. Look for the last execution of the instance above

This way you use Spring Batch API only

//We can set count 1 because job instance are ordered by instance id descending
//so we know the first one returned is the last instance 
List<JobInstance> instances = jobExplorer.getJobInstances("searchExportJob",0,1);
JobInstance lastInstance = instances.get(0);
List<JobExecution> jobExecutions = jobExplorer.getJobExecutions(lastInstance);

//JobExcectuin is ordered by execution id descending so first 
//result is the last execution
JobExecution  je = jobExecutions.get(0);
if (je != null && je.getEndTime() != null) {
     endTime = new DateTime(je.getEndTime());
 }

Note this code only work for Spring Batch 2.2.x and above in 2.1.x the API was somewhat different

Answer 2

Assumption

Spring Batch use some tables to store each JOB executed with its parameters. If you run twice the job with the same parameters, the second one fails, because the job is identified by jobName and parameters.

1# Solution

You could use JobExecution when run a new Job.

JobExecution execution = jobLauncher.run(job, new JobParameters());
.....
// Use a JobExecutionDao to retrieve the JobExecution by ID
JobExecution ex = jobExecutionDao.getJobExecution(execution.getId());

2# Solution

You could implement a custom JobExecutionDao and perform a custom query to find your JobExecution on BATCH_JOB_EXECUTION table. See here the reference of Spring.

I hope my answer is helpful to you.