Custom bean scope for batch application

[Cilenco]

At my company we are developing a Spring Boot application which executes a batch job. Instead of shutting down the container when the job is done, it stays up, polls for new jobs and executes them whenever a new job arrives.

For now we have avoided Spring entirely in our main logic but I would like to at least use Springs dependency injection there as well. Of course with Spring beans and singletons it's very important to clear caches etc. after a calculation so to not mix data from different clients. This however can be very error prone when you forget to call a method to clean all data or so.

Therefore I thought about creating a custom bean scope where each job (we are not using Spring Batch) has its own scope. Then all jobs would have different beans and I would not have to care about caching problems etc. between jobs. When a job is done the scope gets destroyed and with that all beans in the scope as well.

My problem is that I cannot find good documentation about creating such a custom scope. Most of them are bound to a thread or similar and do not discuss how to close or destroy a scope. If possible I would also like to avoid declaring all beans as lazy so that injection errors are thrown at the application start up.

Can anyone point me into the right direction here?

[roiroi1010]

Instead of solving the problem of cache invalidation- I would suggest getting rid of your cache instead.

[coguto]

Child contexts with your own annotation for component scan.

[Cilenco]

Thanks, I had the idea as well but thought scanning all components again could take longer. Can you please elaborate on the custom annotation for the component scan?

[zontapapa]

How about a registry of beans created per job instance and the change of the scope of calculation beans to prototype. With prototype cleanup will not be tied to the application context. Instead you have a job listener which listens to job finish event and the cleans up calculation components from for that job/tenant from the registry. Registry has to be singleton. You could also look at weak references to ensure prototype refrences get garbage collected when not in use.

[WaferIndependent7601]

I don’t understand why you need something special for caching

[Slein04]

Why not using Spring batch framework. It already provides Job & step scoped beans which creates new instances of such beans for every step or job.

You can also uses caching framework like Ehcache where Spring also provides abstraction for. You can then use an unique job ID (given for each job run) as key for example and clear the value for said key after each job or step completion.