How to explicitly close database connection in Spring JPA?

Question

In my project we are using JPA for querying from database. We are facing problem while running the performance and it throws exception connection unavailable.

I did check for other sources online. It is mentioned to add following properties - maxIdle, minIdle, and minEvictableIdleTimeMillis to the data source. I have set above properties along with initial-size, max-active, remove-abandoned, remove-abandoned-timeout, min-evictable-idle-time-millis etc. But it is not working.

Few resources suggest to close connection explicitly. But I am not sure how can I explicitly get the current DB connection in JPA and close it. I have included the code which I am referring.

Any suggestion on this would be very helpful. Thanks in advance.

Repository class:

public interface checkRepository extends JpaRepository<CheckEntity, Long> {
    CheckEntity findById(String id);
}

Service class:
class Service{

    public void method(){
        try{
            checkRepo.findById(id);
        }catch(Exception ex){

        }finally{
            //Close the connection here 
        }
    }
}