batch job using param incrementer can’t be restarted anymore from command line

[christophejan]

Supersedes spring-projects/spring-boot/issues/49569 (please check spring-boot team feedback on it)

With Spring Boot 4.0.3, batches using JobParameterIncrementer can’t be restarted anymore from the command line. Instead of restarting the job instance, İt starts a new instance of the job.

Without JobParameterIncrementer, there is no such issue with restart.

Spring Batch 6 doesn’t forbid to restart a job with JobParameterIncrementer. Such a job can still be restarted as expected when using JobOperator#restart (but not with JobOperator#start()).

JobOperator seems a little inconsistent to me with Spring Batch 6 major changes around JobParameterIncrementer. I don’t know if this restart issue should be fixed on Spring Boot JobLaunchApplicationRunner or on Spring Batch side.

Here is a demo.zip to illustrate the issue.

[nikitanagar08]

I would like to work on this issue. This involves fixing the restart behavior for jobs using JobParameterIncrementer when launched from the command line. Let me investigate the issue and the demo project provided to understand the root cause and propose a fix.

[fmbenhassine]

@christophejan Thank you for raising this and for providing an example.

This is only an issue with the Boot runner, not the Batch runner (I attached a working sample with the Batch runner). The reason is that the Boot runner is nothing more than a job runner (ie no other operations than run/start a job), while the batch runner is more capable with additional operations like stop, restart, etc (that's why we renamed CommandLineJobRunner to CommandLineJobOperator in v6 to better clarify the intent/scope of the class). We tried to expand the Boot runner's capabilities to other batch operations in the past but this was rejected (see spring-projects/spring-boot#12306, which suggests in the last comment to do other operations programmatically if needed).

Spring Batch 6 doesn’t forbid to restart a job with JobParameterIncrementer. Such a job can still be restarted as expected when using JobOperator#restart (but not with JobOperator#start()).

That's correct. Spring Batch 6 still allows to restart a job having an incrementer with a distinct operation, but has removed the confusion that a "start" operation can do an implicit "restart". That implicit behaviour caused a lot of issues in v5 and prior versions, especially with incrementers, see #4910 (and linked issues).

JobOperator seems a little inconsistent to me with Spring Batch 6 major changes around JobParameterIncrementer.

Can you please elaborate on this? To me it is quite the opposite, it is the previous version that was rather confusing. Moreover, JobOperator was improved in v6 regarding its APIs and scope (#4845, #4833).

---

gh-5340-batch.zip